Soundwave decides to take advantage of an empty ship to have some fun in Megatron’s throne, Megatron walks in and finds him, a considerable amount of fun ensues. 

Loosely TFP, but with Megatron actually sane and a decent person. This is like good-ending TFP, basically. No significant warnings. Improper use of data-cables, some awkwardness and general embarrassment, and relatively minor fluid stuffing with a biological basis- i.e. overflow tanks are a thing in Cybertronians and get full when you have a larger-than-you partner. Spike-in-valve smut, little bit of showing off, gets a bit fluffy. Definite praise kink somewhere in there. 

Soundwave very rarely got any time to have the ship to
himself. But, with everyone out on reconstructive efforts and attempts at
socializing, he was left mostly alone. Which meant he had the throne room to
himself for non-urgent reasons for once, and, mm… he had plans.

Plans which were turning out to be a lot of fun to work on.

Nuzzling into the back of the throne, Soundwave rocked his
hips and spread his thighs wider, inhaling deeply to fully enjoy Megatron’s
scent. Strong, powerful… and stil warm. Which made it easier to imagine that
the datacable he’d wrapped around his own frame was the pressure of strong
servos on his hips, to imagine that the cable slooowly pressing into his valve
was a thick spike. Good, good- but not quite as good as the real thing. Which
he should stop thinking, he wasn’t going to get that, and- ah!

Mmh, nice- that was a sensitive spot. Soundwave exhaled
slowly and rocked his hips down again, taking the cable a bit deeper, and
curled the tip slightly to rub against that spot again. Ah, yes- that was good.
Of course it was good- Megatron was an intelligent mech with plenty of
experience, he would know how to find the right spots.

Helm lolling back, Soundwave panted and whined softly, valve
clamping down around the cable, starting to relax completely-

And immediately went incredibly, painfully tense as he heard
the door slide open. Pit- slagging pit- he’d
locked the door! He’d definitely locked- and oh, no, there was only one other mech who had the codes to unlock that
door, and that was-

Curling into himself in embarrassment, Soundwave hunched his
shoulders and tried to pretend he wasn’t there, whining in mortification as
Megatron approached him.

Megatron slowly walked up to his occupied throne, brow
ridges raised, and paused for several long moments before speaking. “…well
then, Soundwave,” he began, then smiled slightly and moved to put himself where
Soundwave could see that he didn’t appear to be upset, “are you enjoying
yourself?”

…yes. Soundwave nodded slightly, once, hunching his
shoulders even further and hiding behind the flat of his arm. Pit- this was
mortifying. He’d been caught pleasuring himself on Megatron’s throne, clearly
thinking of Megatron, and still had the cable pressed into his valve- mostly
because it would hurt to yank out at this point with how tense he was. This was
not how he’d wanted to express his
interest, this was embarrassing- but,
yes, he had been enjoying himself.

Megatron slowly reached to stroke Soundwave’s arm, coaxing
the spymaster’s servo down away from his face, and pulsed a field full of soft
reassurance to the flustered mech. “Well then… my apologies for disturbing you.
Now… I have a question, and you are free to think before answering. Do you want
me to leave so you can continue enjoying yourself here, or do you want me to
join you? I am open to either option… though I confess I would prefer the
latter.”

Firmly meeting Soundwave’s optics, the former warlord slid
one servo down to touch Soundwave’s narrow claws, trying to ease their tight
grip on the edge of the throne. “Please understand, you are under no obligation
to let me touch you. Easy- you know me, Soundwave, you know I would never hurt
you. And you have my word I will leave if you ask. So… with that in mind…”

Purring gently, he loosened Soundwave’s servo and lifted it
to his lips for a soft kiss, trying to charm the nervous mech into relaxing.
“Do you want me to join you?”

Oh.

Yes. Primus, yes, absolutely. He couldn’t see why Megatron
would want him, given how many mechs
would more than willingly berth
Megatron and had expressed their interest in the past, but… oh, if Megatron
wanted this, absolutely.

Soundwave nodded slightly, optics wide, and slowly turned to
face the larger mech. He… wasn’t certain how to start here, but yes. Please.
Because he trusted Megatron- he knew his Lord wouldn’t hurt him, would never
hurt anyone like that, but especially not him.

Megatron held Soundwave’s servo gently between his own,
engine purring in approval, and slowly moved to stand in front of his throne
where he could look Soundwave over. “Thank you, Soundwave,” he purred, his tone
as soft as he could manage, not wanting to spook the still-tense spymaster into
running. Poor mech didn’t deal well with embarrassment, he was shy. Time to
reassure him.

“Let me be clear, Soundwave. You are allowed to refuse at
any time, and I will not be upset if you change your mind. If you are
uncomfortable at all or have a request, please
tell me. Anything you want, I will be delighted to oblige. Am I understood?”

He waited for a nod, then purred softly and leaned down
slightly, projecting interest/arousal/reassurance
to the pretty spymaster in his throne. “Good. Now- turn around, Soundwave,
get comfortable, and slowly pull that cable out of your pretty valve. Let me
see you. The rest of you is so lovely… I want to see what your equipment looks
like.”

Oh, Primus. Optics
dimming slightly, Soundwave nodded and slowly turned around, optics flicking
between Megatron and the floor. Shy, he eased his thighs apart and glanced up
at his watcher, biting his lip, then slowly eased his data-cable out of his
valve. He’d… never done anything like this for an audience, but the way
Megatron was looking at him made fire curl in his belly and wrap up around his
spark chamber. That was- oh, Primus, admiring.
Lustful, yes, but not threatening, not
like he wanted to take something- like he was delighted that Soundwave was
willing to give him this.

So he let Megatron see his valve, then he took it one step
further, wrapping the lubricant-coated cable around his thigh and pulling his
legs apart. He could feel himself
blushing, but Megatron purred in
approval, the sound drawing a flutter from his spark, and… oh. He wanted more
of that.

So, shy but more than willing, he lowered a servo and spread
his valve lips open with two careful fingertips to show off the lights.  

Pulsing stronger approval/arousal
to Soundwave, Megatron stepped closer and gently slid his servos around the
spymaster’s frame, lifting very gently to start shifting him around. “Oh, such
a beautiful mech. So, so lovely, and so smart.
Whatever made you think I wouldn’t be interested in you, Soundwave? You are
gorgeous, intelligent, and charming,” he
purred, then chuckled at a questioning little glance. “Yes, you heard me,
charming. In your own, precious way. If you had asked me, I would have very gladly accepted, just like now.
Here… let me get you comfortable. Just relax for me.”

Soundwave was light, and it was no effort whatsoever
for Megatron to lift the lanky mech enough to sit down where he had been a
moment ago. He could feel Soundwave quivering
against his servos, tightly coiled field buzzing anticipation/excitement/intrigue/arousal/nervousness against Megatron,
but the spymaster was moving with him and there was no fear in his
oh-so-expressive optics. Maybe a bit nervous, but clearly willing, exposed
valve radiating heat against Megatron’s plating as they settled into place.

Engine rumbling soothingly, Megatron set Soundwave in his
lap and stroked the spymaster’s back with one servo, gently splaying those
gorgeous thighs around his hips with the other servo. “There we are, Soundwave.
Comfortable? Good. Now, beautiful… I would like to spike you. You have such a
pretty valve, and… I imagine that’s what you were thinking of, hm? My spike in
your valve? I confess, I very much hope so, because…”

Pausing, he gently palmed one of the spines along Soundwave’s
back, rubbing it between his fingertips in a fairly suggestive gesture as he
purred his desires to the gorgeous mech in his lap. “I want very much to feel
your valve around my spike. I want to see you in my lap, want to see you in
pleasure… I want to watch you ride my spike and take your pleasure with me. I
am open to other suggestions, but… what do you think of that?”

Okay. Soundwave
nodded quickly, then whined quietly, flustered, and pushed his face into
Megatron’s shoulder to hide. Yes, yes- absolutely. That was his exact fantasy, Primus- him in Megatron’s
lap, riding his Lord’s spike, in control-
Primus, he wasn’t about to refuse that. Especially not combined with
reassurance. And praise, Primus take
him now, Megatron was praising him
and it was sincere. Soundwave knew
the voice that Megatron used to flatter others, and that wasn’t it.

…other people didn’t get this turned on by praise, did they?
Because he knew praise kinks existed, but this was unfairly hot and was making it very difficult to focus. But, for
this, he would try.

Settling his frame against Megatron’s, Soundwave slowly
rocked his hips against the larger mech’s, breathing a quiet sigh of pleasure
as he rubbed his valve over the heating pelvic plating under him. Without his
cable spreading his valve open, he felt empty,
and he wanted something. Specifically, he wanted Megatron’s spike inside
him. As close to now as possible. Giving a quiet, pleading warble, he ground a
bit harder against the closed panel, trying to coax Megatron to-

Oh dear.

Megatron shifted before opening his panel, making sure that
his pressurizing spike wouldn’t end up pressing too hard on Soundwave’s valve,
and cupped his servos against the slender mech’s aft for support. He’d felt
Soundwave twitch away from him, and he could understand why- his spike would be
a stretch for someone close to his size, and Soundwave had lanky hips.

Careful not to trap
the spymaster, he rubbed gently at Soundwave’s lower back with one servo,
slowly easing the other down his aft until he could just touch the lower edge
of that pretty purple valve- a soft tease. “Easy, Soundwave. You have nothing
to worry about- we can go as slow as you need. I will not cause you pain, I
promise. Here- rub against me first, see how I feel against you. Figure out if
we need to stretch you open further before we proceed. And- listen. If you do
not think you can comfortably fit my spike, we can do something else. We are
both clever mechs, we can come up with alternatives. See how you feel, then let
me know.”

Relaxing again at the reassurance, Soundwave settled back
into place and looked down at Megatron’s spike, slowly wrapping a data-cable
around it to feel it out. Unsurprisingly, it was fairly large, wider than
anything Soundwave had taken so far. But… not by too much, and, unlike his
cable, shaped to fit a valve. And there were a series of ridges along the upper
edge that he… rather wanted to try out. So… a large spike, yes, but-

Well, the thing that helped make up his mind was that it was
attached to Megatron. Megatron, who would never hurt him, was purring
reassurance to him and rubbing his back and waiting
despite the growing arousal in his field. This was safe- just as safe as
playing with a toy back in his quarters, except with Megatron. Which was delightful, not just for the warmth and charge
and sensations, but for the praise and
for the mech he trusted, the mech he adored,
holding him close. Primus.

So he took the offer. He could do this- he could take
Megatron’s spike, absolutely. Or- at the very least, could do something with it, something to bring
them both pleasure.

Optics on Megatron’s face, he lifted himself up and slowly ground
his valve against that impressive shaft, panting softly in arousal and
anticipation. And, oh, already an
improvement over his toys, because there was charge jumping between them as he
rocked against Megatron, and because his Lord was purring in pleasure against him.

Lowering his data-cable to wrap around just the base of
Megatron’s spike, Soundwave carefully lined himself up, then rocked his hips
down in one slow motion. He was wet enough that it was an easy slide, the tip
of that pretty spike slipping easily into his valve, and he paused like that to
consider the sensation before offering Megatron a nod and a tiny smile. Yes- he
could absolutely do this. Might need some time, but he could. Could absolutely
do this… just lower himself, nice and slowly, and stop if he had to.

Optics dimming, he settled against Megatron’s frame and
purred softly, unfurling his field to purr bliss/arousal/anticipation
to the larger mech as he started to press down further.

It took more than a little effort for Megatron to stay still
as that hot, tight valve started to wrap around his spike, but he managed it.
Mostly because he absolutely refused to buck into Soundwave, not with how tight
the spymaster was. No matter how teasing it got, he was not going to risk making Soundwave even slightly uncomfortable.
Besides, there were nicer things to focus on right now.

Whispering “that’s it, be gentle with yourself”, he cupped
one servo against the side of Soundwave’s helm, pressing his thumb to deep blue
lips until they parted for him. Sharp dentae gleamed in the light as they slid
apart, and Megatron purred in approval as Soundwave’s flexible glossa wrapped
around his thumb. “This is lovely- so unique. I would –ah- love to feel this against my valve, if you would be willing. But-
for now, a kiss, sweet?” he whispered, and grinned when Soundwave immediately
pressed against his servo.

As soon as Megatron took his servo out of the way, Soundwave
leaned up to kiss him, awkward but very eager. It was more than rare for
Soundwave to be awkward, but it was cute,
and Megatron purred as he returned the kiss. As he’d thought, that slender
glossa twined easily with his, muffling a groan of pleasure- and Soundwave’s
field finally blossomed open fully into a shimmer of pleasure/anticipation/nervousness/trust. Even better than the kiss.

Soundwave eventually leaned back away from the kiss, mostly
so he could pant for more air, then moaned and rocked down a bit further. There
was a stretch, but nothing unpleasant, and Soundwave crooned a soft, shaky
noise up at Megatron as he felt the first of the ridges press against the rim
of his valve. Another rocking motion, this one much smaller, and the ridge
popped inside in a quick flare of pleasure.

Megatron’s engine was purring louder against him, field
rumbling arousal/bliss/pleasure, and
Soundwave wanted to feel more of that- wanted to get more pleasure, to give more, so he slowly lifted up and
rocked back down a couple of times in an effort to loosen his calipers up.

An effort that worked, pulling a startled, staticky cry of
pleasure from him as he sank down much further than intended. OH, Primus-

Megatron inhaled sharply, hips twitching up despite his best
efforts, and steadied Soundwave’s frame with both servos to keep him from
sliding down further. “Ah, Soundwave-
easy, are- nnh- are you all right? You feel… amazing, gorgeous, so hot, and your optics- you are beautifully expressive, do you know that? Such
bright optics, so sweet- I can see your pleasure unfold.”

Vents gusting hot air to help cool his frame and keep his
control, Megatron cupped a servo against Soundwave’s aft and squeezed lightly,
sliding the other servo up his partner’s side to brush over the glowing lines
in his stomach. And, ah- apparently
Soundwave was more than all right, because it only took a few deep vents for
the spymaster to start working himself down again, this time stopping tantalizingly close to taking his entire
spike.

“That’s it, Soundwave- so good, and, mm, impressively flexible- come on, just a bit further?
You can do this, gorgeous- one more little motion, sweet?”

Megatron sounded almost needy,
and it reached Soundwave even through the haze of pleasure. Oh- he’d been
rather slow about this, hadn’t he? And he didn’t want to keep Megatron waiting,
so he pulled himself up, paused for half a nanoklik, and rocked down again-
and, this time, felt his node grind against the area just above the base of Megatron’s
spike.

Helm lolling back, he moaned softly and loosened his bracing
grip on- whoops, he was digging his claws into Megatron’s upper arms. Offering up
a soft smile, he let his data-cables wrap down and around the warlord’s frame,
then lifted Megatron’s hips at the same time as he propped himself up slightly.
He wanted to feel Megatron, wanted to
feel those ridges slide in and out of him, but his knees had decided not to
cooperate and he wasn’t sure he trusted himself to move steadily. So- he could
leave it up to Megatron, ri-

Ooh-

 

Whispering “thank you, beautiful”, Megatron slide his servo
down from Soundwave’s aft to hook under his thigh, supporting him gently as he
thrust up into that beautiful valve. Not hard, just a slow, gentle motion, then
again, rocking in and out of Soundwave and gradually easing him open further. And
talking to him the entire way, having already figured out how much Soundwave
liked it. “So good… that’s it. Let me hear you, beautiful… let me hear your
pleasure?”

To his delight, Soundwave obliged. Every thrust from then on
drew a soft, staticky cry from the spymaster, gradually getting louder as
Megatron started to thrust harder. When the thrusts no longer met any resistance,
Megatron lifted Soundwave a bit higher, pulling out further than before and
then thrusting harder. The deeper, stronger thrust earned a louder cry, but,
just to be sure, he paused to ask- he needed to be certain it felt good. “Soundwave,
my sweet- such beautiful sounds, but- do you like that? Do you want more?”

Soundwave was caught a bit off guard by the deeper motion,
but Pit yes, he wanted more. Much
more. Warbling the steadiest affirmative he can manage, he pushed himself up
and sank back down to mimic the motion, then relaxed completely against
Megatron- leaving it up to the larger mech to decide what happened from then on.
Ohh dear Primus- that was it, he was done. This was amazing, and he absolutely wanted more, but his knees were still
uncooperative and the praise had him
wanting to do nothing more than just bury his face in Megatron’s throat and
moan.

Gripping onto the warlord’s arms in anticipation, Soundwave
gently squeezed the powerful frame with both data-cables, trying to encourage-
then gasped as Megatron did exactly what he wanted Megatron to do. Namely,
lifted him up and then brought him back down to meet the next thrust, rubbing
the ridges on that lovely spike along the inside of his valve rim.

“Ah- thank you for your trust, Soundwave, “ Megatron purred,
then gave up on coherent speech for now and just continued to thrust, reveling
in the sounds of bliss he was earning. Soundwave’s servos were gripping his
plating tight enough to dig the clawtips in, but he couldn’t bring himself to
care in the slightest, and the rhythmic squeezes of the powerful data-cables
around his frame only served to spur him on. Soundwave was beautiful, glowing frame and half-static voice alike, and to hear
his loyal friend in such pleasure was absolute bliss.  

And there were benefits to having such a light partner, one
of them being that he could easily shift the angle of Soundwave’s hips to try
for different, better spots. A careful motion, then another, then a slight
angle back, and-

Completely past shame, Soundwave squealed in pleasure as the calipers at the very back of his valve
clamped down around the tip of Megatron’s spike, rocking his hips down and into
the thrust to feel the friction against- what was that?

Frame tensing, Soundwave held himself in position, a hint of
curiosity flickering through everything else in his optics, then moaned quietly
as he realized what that must be. Well- as it was realized for him, by a soft spreading feeling deep in his belly. That must be the entrance to his
overflow tank opening, he hadn’t felt it before but it must be, it made sense, and-

And his next cry was a quiet, pleading whine, accompanied by
another rock of his hips, trying to get Megatron to-

He knew the function of an overflow tank, and, since there
was no risk of any unintended consequences, he wanted to experience at least
part of that function for himself. He wanted- Primus, he apparently wasn’t quite
past embarrassment, but he wasn’t even remotely
ashamed of wanting to feel Megatron fill
him.

 

“Easy- I have you, Soundwave, my beautiful, loyal friend,”
Megatron purred, sliding one servo up Soundwave’s back to offer more support
and pull him closer, and began to rock into Soundwave’s valve again. Small,
quick motions, not too hard or deep, meant to stimulate those deep nodes- and
to help hasten his own overload. He’d felt that shift against the tip of his
spike, he could guess what Soundwave was trying to ask for, and he knew how to
give it.

Growling in pleasure as he felt Soundwave’s claws skitter
against his plating, Megatron held his partner as close as he could while still
able to move, releasing enough of his control to let his charge build with no
restraint.

Keening against Megatron’s chassis, Soundwave dug his claws
in to brace himself against Megatron’s thrusts and let himself voice every
clear sound he could manage, trying to encourage the warlord to- yes, Primus,
to keep doing exactly this, please, more-

He could feel Megatron’s charge building, could feel it crackling
around both their frames, and Megatron was still calling him things like ‘beautiful’, and that was a very good spot being rubbed against with
an impressive amount of strength. Biting down on the plating he was nuzzling
into, Soundwave skreeled in pleasure as Megatron thrust once more- twice more-

And then his awareness spiraled down to nothing but the wet,
charge-filled heat flooding deep
inside him as Megatron overloaded. Overload hit Soundwave just a nanoklik
after, bouncing some of Megatron’s charge back to him, and the spymaster wailed
shakily against the plating his dentae were digging into. Every bit of his
frame curled around and against Megatron, valve calipers rippling around the
thick spike spreading him open, then he went limp into the larger mech’s lap
and moaned up at him.

Oh, Primus. He’d-
he’d never felt anything to do with his overflow tank before, toys didn’t work
for that unless they were specialized, but the novel stimulation of a large
partner must have done the trick. And now… now he had a spike filling his valve
so thoroughly that almost all of Megatron’s transfluid had ended up in his
overflow tank, and… mmh.

Wow.

…why hadn’t he asked about doing this before?

Okay… time for a reboot, everything was… sluggish.

Megatron purred softly and gathered Soundwave up, pressing a
kiss to his audial fin, but carefully didn’t pull out of the spymaster’s valve.
He’d leave that to Soundwave. “Such a pretty mech… oh, so, so pretty. And I
love your voice, Soundwave.
Different, but… still you, my lovely.
Oh… are you all right?”

Ah. Must have been a delayed reboot. Humming, Megatron
stroked circles on Soundwave’s back and sides, brushing away remaining
fragments of charge, and held him gently until he started to stir. “Ah, there
you are. I take it you’ve had fun?”

Yes.

Soundwave bumped his face into Megatron’s throat, trying to
communicate… something nice, he wasn’t sure yet, and squirmed around his stuffed valve and overflow chamber. That- okay,
that was a bit much, and he whined quietly and clawed his way up Megatron’s
frame until his partner got the message and gently pulled out.

That didn’t ease all of the pressure, though. His overflow tank
was definitely full and had closed to
stay that way, and Soundwave cupped a servo across his stomach to help himself
focus on the heat. Which allowed him to register the very slight swell in his own stomach, from… well, Megatron was larger than him, might not have had a spike overload in awhile, and… hm. The end result was Soundwave’s overflow tank stretching to accommodate everything. It felt strange, but it was a very nice sort of strange, and much less messy than the
alternative. Though this was still messy… partly thanks to his own valve, there
was a considerable amount of lubricant slicking his thighs. Which didn’t feel
excellent.The full overflow tank, though? That felt excellent. Made him blush even more, but… wow. 

As soon as his frame was steady enough, Megatron stood up
with Soundwave in his arms, easily supporting the spymaster’s lanky frame with
one servo on his back and the other arm slung under his aft. “Relax- let us get
you cleaned off, Soundwave. We have some time before everyone else gets back,
so… unless you have any suggestions, I am going to take you to the washracks,
get you cleaned up, and then… I would like to take you back to my quarters.
What happens next is entirely up to you, but I would like to keep you curled
against me like this for longer. You are warm, you purr nicely, and I have
never felt you this relaxed. I would
like it to continue. Are you open to that?”

Judging by the quiet, shaky,near-musical crooning in his
audials, Soundwave was very open to this whole situation.