Being the boyfriend of Dynamight, the hottest hero on the market,...
Sapphire Midnight@SapMidnight
69 views
Aug 31, 2026
~10 min read
1
Being the boyfriend of Dynamight, the hottest hero on the market, isn't a flex that Izuku really cares about.
Being Kacchan's boyfriend, however, IS something he's quite proud of. And he knows Kacchan feels the same.
But some people don't agree.
#BKDK #BakuDeku #SpicyBKDK
Being Kacchan's boyfriend, however, IS something he's quite proud of. And he knows Kacchan feels the same.
But some people don't agree.
#BKDK #BakuDeku #SpicyBKDK
2
He knows he isn't perfect, like most social media portrays him. Kacchan likes to point out all the weird or dumb things he does when it's just the two of them.
But in his mind, the one flaw he's had since childhood is his possessiveness of Kacchan.
And he uses 'flaw' loosely.
But in his mind, the one flaw he's had since childhood is his possessiveness of Kacchan.
And he uses 'flaw' loosely.
3
He's been in love with Kacchan his whole life. Most don't understand their dynamic, because they take Kacchan's explosive nature and mean barbs as truth.
They don't see his soft hands cleaning Izuku's wounds after work, Kacchan's loving lips kissing his forehead goodnight.
They don't see his soft hands cleaning Izuku's wounds after work, Kacchan's loving lips kissing his forehead goodnight.
4
He gets why some see their outside dynamic and think they can get between them. How can someone as beautiful and amazing as Kacchan be satisfied with a plain-looking Deku?
And Izuku thinks that until he learns something... unbelievable.
Kacchan thinks he's sexy when jealous.
And Izuku thinks that until he learns something... unbelievable.
Kacchan thinks he's sexy when jealous.
5
"I find you sexy all the time," Kacchan clarifies in their bath, the wine of their three-year anniversary letting loose lips kiss along the slope of Izuku's neck.
Izuku leans his head back, simmers in the touches teasing his thighs under the water. "Ah, but you're the attrac-"
Izuku leans his head back, simmers in the touches teasing his thighs under the water. "Ah, but you're the attrac-"
6
A bite breaks up his protest with a moan, leaving Kacchan time to smirk against his shoulder. "But there's something about Japan's sweetheart getting jealous over me that makes me wanna fuck you more than normal."
Izuku shudders, trying to rock back into Kacchan's lap. "Really?"
Izuku shudders, trying to rock back into Kacchan's lap. "Really?"
7
"Duh." Then the hand on his thigh slides up, and their conversation gets lost between pleasured sighs and moans.
He doesn't know if Kacchan's comment is to tease him or urge him to do it more. Maybe a bit of both.
Either way, it doesn't stop Izuku's envy from showing up.
He doesn't know if Kacchan's comment is to tease him or urge him to do it more. Maybe a bit of both.
Either way, it doesn't stop Izuku's envy from showing up.
8
Izuku never brags openly about their sex life, knows he couldn't stand the public teasing if he did.
Except his mind forgets his reasons not to stake his claim when they're at a charity event the following week.
"Oh, don't look now, but someone's playing with explosive fire."
Except his mind forgets his reasons not to stake his claim when they're at a charity event the following week.
"Oh, don't look now, but someone's playing with explosive fire."
9
Hanta's whistle after his words makes Izuku look from the conversation with Jirou to see what he's talking about.
Like always, he looks for Kacchan and hates what he sees.
He recognizes the reporter leaning against Kacchan's arm, batting his eyes at the hero. It's... flirty.
Like always, he looks for Kacchan and hates what he sees.
He recognizes the reporter leaning against Kacchan's arm, batting his eyes at the hero. It's... flirty.
10
Izuku could laugh it off, except he knows this man. He revealed Kacchan's sexuality before he was ready to come out.
Now he thirst blogs about his boyfriend, like he didn't make Kacchan break down in Izuku's arms. Like the exploitation didn't almost destroy his favorite person.
Now he thirst blogs about his boyfriend, like he didn't make Kacchan break down in Izuku's arms. Like the exploitation didn't almost destroy his favorite person.
11
Kacchan deserves to know how pretty he is. People fawning over him is an expectation.
But the way this man ignores Kacchan's (who somehow hasn't blown up and thrown the reporter across the room) tense frame pokes his jealousy into a new mode.
He needs to protect what's his.
But the way this man ignores Kacchan's (who somehow hasn't blown up and thrown the reporter across the room) tense frame pokes his jealousy into a new mode.
He needs to protect what's his.
12
Izuku barely keeps his manners pushing through the party to get to his boyfriend, but he makes his presence known quickly.
"Kacchan!" Izuku almost sings his name when he leaps forward, arms linking around his taller boyfriend's neck.
Which pulls him away from the reporter.
"Kacchan!" Izuku almost sings his name when he leaps forward, arms linking around his taller boyfriend's neck.
Which pulls him away from the reporter.
13
Kacchan barely stumbles before he adjusts to his weight on his side, and Izuku preens when a large hand grabs his waist despite the red glare.
"Oi, watch what you're doing. You trying to get hurt?"
Izuku hopes he's sheepish enough to hide his intent. "I knew you'd catch me."
"Oi, watch what you're doing. You trying to get hurt?"
Izuku hopes he's sheepish enough to hide his intent. "I knew you'd catch me."
14
"Idiot." Except the eye roll loses any snark when the scowl Kacchan's worn all night fades away.
Delighted at how his appearance changes Kacchan's ambiance, he peeks over at the almost frowning reporter. His fingers stroke the blonde hair on his nape, possessively.
A claim.
Delighted at how his appearance changes Kacchan's ambiance, he peeks over at the almost frowning reporter. His fingers stroke the blonde hair on his nape, possessively.
A claim.
15
But he grins with a brightness that nobody can challenge. "Oh, were you doing an interview with Kacchan?"
"Well-"
His mother would scold him for cutting the man off (until she learned who it was. Then she'd make him katsudon.) "Sorry, I just missed my boyfriend. He's amazing."
"Well-"
His mother would scold him for cutting the man off (until she learned who it was. Then she'd make him katsudon.) "Sorry, I just missed my boyfriend. He's amazing."
16
"Did Round Cheeks gets you tipsy again?" Despite the accusation, his cheek gets a nip he knows the man watching would die to feel.
"No." Okay, so he's had a little to drink, enough to not-so discreetly press his hips against Kacchan's thigh. "You just look really nice tonight."
"No." Okay, so he's had a little to drink, enough to not-so discreetly press his hips against Kacchan's thigh. "You just look really nice tonight."
17
The man's fuming his 'moment' (that Izuku knows was only in his head) is stolen by Izuku's arrival. Its probably bad to feel a surge of pride at how easily Kacchan's attention shifts to him just by showing up.
"You're such a little creep."
Kacchan's comment gives the man hope.
"You're such a little creep."
Kacchan's comment gives the man hope.
18
"Dynamight doesn't seem to be a fan of public displays of affection. It can be tacky."
Maybe two years ago, the passive-aggressive comment would make him second guess his confidence.
But too many nights of Kacchan worshipping every dorky freckle on his skin blasts it away.
Maybe two years ago, the passive-aggressive comment would make him second guess his confidence.
But too many nights of Kacchan worshipping every dorky freckle on his skin blasts it away.
19
Instead, he uses what he's learned from long nights of passion to his advantage. Rounding his eyes to hold innocence he lost to the explosive hero, he entwines one leg around Kacchan's.
It leans his weight into Kacchan's side, the length of his compact body pressed against him.
It leans his weight into Kacchan's side, the length of his compact body pressed against him.
20
The world shrinks to just them.
"Deku, you good?" Kacchan asks, secretly sweet.
Izuku moves a hand to wrap around the back of Kacchan's shoulder, the other fully cupping the sweaty nape.
Just loud enough for nosy reporters to hear, he asks "Remember our bath night together?"
"Deku, you good?" Kacchan asks, secretly sweet.
Izuku moves a hand to wrap around the back of Kacchan's shoulder, the other fully cupping the sweaty nape.
Just loud enough for nosy reporters to hear, he asks "Remember our bath night together?"
21
Even through his suit, the palm heats his hip at the memory. "Which round? Gotta be more specific, Freckles."
The name only comes out when they're alone, normally when most of the said spots are exposed for Kacchan's exploration.
Just hearing it makes his dick twitch, needy.
The name only comes out when they're alone, normally when most of the said spots are exposed for Kacchan's exploration.
Just hearing it makes his dick twitch, needy.
22
But the reporter, the one who once made Izuku fear he'd never get to hold Kacchan's hand in public, is still watching them. He believes in karma, but... maybe he can help it along.
So he slips his fingers into Kacchan's hair and tugs him down, close enough to whisper in his ear.
So he slips his fingers into Kacchan's hair and tugs him down, close enough to whisper in his ear.
23
"I don't like how he touched you." Despite Kacchan already saying he likes this, Izuku still flushes while he confesses. "I kinda wanna Detroit Smash him right now, so I need- can we go somewhere alone? Please?"
He expects a smirk. A scoff. A taunt.
Instead, Kacchan lifts him.
He expects a smirk. A scoff. A taunt.
Instead, Kacchan lifts him.
24
"Kacchan?!" Izuku's legs wrap around sturdy hips before remembering they're at a charity event.
He squeaks when a hand smacks his ass, and he can only bury his flushed face into Kacchan's neck.
"Oi, extra. I'm gonna go fuck my boyfriend. Put THAT on your next shitty blog."
He squeaks when a hand smacks his ass, and he can only bury his flushed face into Kacchan's neck.
"Oi, extra. I'm gonna go fuck my boyfriend. Put THAT on your next shitty blog."
25
He should scold Kacchan for being so vulgar to the gaping citizen, but he stays silent, shivering against the warm chest.
Maybe he waves while Kacchan carries him toward the exit, biting his lip at the delicious way his hips rub into Kacchan's stomach from the quick steps.
Maybe he waves while Kacchan carries him toward the exit, biting his lip at the delicious way his hips rub into Kacchan's stomach from the quick steps.
26
The wall Kacchan pushes him against isn't safe enough for the hot kiss slammed on his mouth.
Feet still dangling from the tight hold, Izuku can only squirm and try to arch up into the passionate exchange.
The party's drowned out when he moans into firm lips. "Kacchan, please-"
Feet still dangling from the tight hold, Izuku can only squirm and try to arch up into the passionate exchange.
The party's drowned out when he moans into firm lips. "Kacchan, please-"
27
"You really thought that fucking loser would ever have a chance with me?" Kacchan is jerking their clothes just just to expose the skin he wants to devour.
Izuku hits his head against the wall when trying to arch his neck for the teeth sinking into the spot just under his ear.
Izuku hits his head against the wall when trying to arch his neck for the teeth sinking into the spot just under his ear.
28
Kacchan shoves his palm behind his curls to keep him from hurting his head. "Knock that off. Can't fuck you if you're unconscious."
The threat only makes Izuku bite back a whine. "Want you inside. Wanna be yours."
Of course, Kacchan scoffs. "You've always been mine, Deku."
The threat only makes Izuku bite back a whine. "Want you inside. Wanna be yours."
Of course, Kacchan scoffs. "You've always been mine, Deku."
29
The way Kacchan manhandles him to drop his legs and turn him toward the wall shouldn't be so arousing. His cheeks flush when strong hands yank his pants down, expose his ass with another tug to his boxers.
Without words, Izuku's already parting his legs to give better access.
Without words, Izuku's already parting his legs to give better access.
30
"We just fucked before coming here, and you're still acting so needy." The degradation's soft enough for both to get what they want without triggering bad memories. "Like you'll fall apart if I even look at someone else."
This comment makes Izuku huff. "Y-You're no better."
This comment makes Izuku huff. "Y-You're no better."
31
"Cause that's expected." He doesn't know if he's embarrassed or grateful when wetness brushes his rim, wonders if Kacchan keeps lube in his pocket for him. "People know I'll kill anyone who touches what's mine. But you?"
He scratches the wall when two fingers sink inside. "Ah!"
He scratches the wall when two fingers sink inside. "Ah!"
32
"Nah, nobody expects you to flaunt me around like something you've stolen from them."
He wants to feel shame, but the pleasure filling his already shaking body proves the truth; he doesn't regret any of his possessive behavior, so long as it keeps the man kissing his ear close.
He wants to feel shame, but the pleasure filling his already shaking body proves the truth; he doesn't regret any of his possessive behavior, so long as it keeps the man kissing his ear close.
33
So he doesn't protest, reaches to grab his boyfriend's wrist and press now three fingers inside deeper. Both moan as his body clenches from the intrusion, though it's not what Izuku really wants.
He looks back, determined to make his claim clear. "Because you're mine, too."
He looks back, determined to make his claim clear. "Because you're mine, too."
34
Kacchan's pretty with wider eyes, but the surprised reaction to his passionate declaration shifts to a feral smirk. "Like anyone else could keep up."
Another shuffle of clothes pushes bare hips together. Izuku's eyes flutter close when Kacchan slides inside.
Where he belongs.
Another shuffle of clothes pushes bare hips together. Izuku's eyes flutter close when Kacchan slides inside.
Where he belongs.
35
They're loud for their semi-public environment (though no interruptions proves Kacchan picks a safe spot), but Izuku never can stop his noises when being taken care of so well by his talented lover.
Kacchan makes sure to thrust harder any time he thinks Izuku's muffling himself.
Kacchan makes sure to thrust harder any time he thinks Izuku's muffling himself.
36
Increased sweat and panting builds as they race toward their orgasms. Izuku's hand finds a spot on Kacchan's nape again when a smoother palm slips into his disheveled pants, wrapping around his leaking tip.
The blunt pleasure jerks his whole body, and Kacchan almost growls.
The blunt pleasure jerks his whole body, and Kacchan almost growls.
37
A shift of the hips behind him hits him just right, and Izuku keens without care about who hears. Maybe a dark part of him wants to be heard, needs people to see this side of them.
"Yeah? Wanna get caught?"
Kacchan's taunt means he's rambling his lust-drunk thought out loud.
"Yeah? Wanna get caught?"
Kacchan's taunt means he's rambling his lust-drunk thought out loud.
38
Before he can even shake his head in denial, a heavy breath coils around his ear, the hand around him moving faster with heated words. "You hoping someone sees me fucking you?"
"No," He gasps, even as he thrust between the two sensations. "Nobody else can see you li-like this!"
"No," He gasps, even as he thrust between the two sensations. "Nobody else can see you li-like this!"
39
A chuckle makes him shiver, even as it tugs on something hot in his stomach. "Yeah, there's my jealous nerd."
The possessive tone, with the tight squeeze over his dick and a deep stroke inside him, finally makes Izuku reach his peak.
He comes apart screaming Kacchan's name.
The possessive tone, with the tight squeeze over his dick and a deep stroke inside him, finally makes Izuku reach his peak.
He comes apart screaming Kacchan's name.
40
Izuku barely notices getting pressed into the wall as Kacchan uses him roughly to hit his own climax. None of it matters, endorphins buzzing through any hint of discomfort or pain.
But he does give a weak moan when Kacchan sucks a dark mark into his neck.
He likes the claim.
But he does give a weak moan when Kacchan sucks a dark mark into his neck.
He likes the claim.
41
Tomorrow, he'll die when 'Top two hero's sexy escape' covers every social media outlet he owns.
He'll scold Kacchan after seeing the huge hickey Ochaco's make-up can't cover.
But if he touches it and smirks when passing the reporter during his patrol, he thinks it's worth it.
He'll scold Kacchan after seeing the huge hickey Ochaco's make-up can't cover.
But if he touches it and smirks when passing the reporter during his patrol, he thinks it's worth it.
42
I love jealous/possessive Izuku and proud/shit-starting Katsuki. It's my bread and butter.
Hope you like this, and be ready for Sing to Me's new chapter in a few hours!
And come vote on this poll (the more interest shown, the more likely I'll write)
Hope you like this, and be ready for Sing to Me's new chapter in a few hours!
And come vote on this poll (the more interest shown, the more likely I'll write)
Sapphire Midnight@SapMidnight
It's official...I'm on VACATION 🥳
So to celebrate while you wait for the spicy BkDk 🧵/STM's new chapter, vote in this poll.
IF (not guarenteed, still debating interest in it) I wrote a pregnancy au, what would want the BkDk dynamic to be of how they accidentally got preggo?
So to celebrate while you wait for the spicy BkDk 🧵/STM's new chapter, vote in this poll.
IF (not guarenteed, still debating interest in it) I wrote a pregnancy au, what would want the BkDk dynamic to be of how they accidentally got preggo?
