So, basically I lowkey wanted to try writing smut, but using my self-insert/BNHA OC, Ellen-Andrew/EA/'Hiei'/Ace, the Magical Guardian Hero. Ace is nonbinary, aromantic, and asexual. Their quirk is Hard Light, which allows them to create structures of hard light but is limited by surface area and their own energy levels. They use their quirk for a variety of things, including as a binder under their costume. They have a 'magical girl' type theme with their costume. Their nickname, 'Hiei', comes from the initials of their name, EA.
Taylor/Ricochet, the Resilient Heroine, is the erotic friend fiction counterpart of one of my close friends. Her quirk, Belly Drum, causes physical hits against her to bounce back with twice the force. She's pan and in a polyamorous queerplatonic relationship with EA and her boyfriend Anthony. She's the only one EA permits to call them only 'Ellen'.
Ken Kobayakawa/Soapboy, the Bubble Hero, is basically Jo2uke/Gappy Higashikata from JoJolion, but transferred to the BNHA universe. His quirk is Bubbles. Instead of a stand, he can form bubbles that can absorb/steal traits and materials. This does not work on himself, though. His costume is basically what canon Jo2uke wears: an ill-fitting sailor suit.
In this universe, EA and Taylor are American transfer students attending U.A. in class 3-A. Ken is also in 3-A.

I dunno, I sort of just wanted to write porn from an asexual character's point of view.

"-ei? EA? Please, EA! Ellen!"

Is that… Taylor? There's something shaking their shoulder, too. Ellen-Andrew groaned, cracking their eyes open a sliver to see Kobayakawa crouching next to them.

"Oh, thank goodness! You're okay!" he says.

EA sat up slowly, taking in their surroundings. They're in an underground tunnel, with rough concrete walls and hard-packed dirt floor. Oh, yeah, we were here on a drug bust. There's a slight draft coming from somewhere to their left, but there's no light save from the soft glow from their binder underneath their costume and the blue bioluminescence of scattered patches of moss throughout the small space. EA's headset lies on the ground next to them, Taylor's tinny voice repeating itself through it. They carefully pick it up. "I'm alright, Ricochet. Soapboy's here, too."

At this response, Kobayakawa stands slowly, smiling widely in relief. Part of his costume is ripped, showing the ugly mesh sweater he wears underneath.

"What happened?"

Taylor's voice crackles back across the radio. "Bakudan miscalculated the radius when he was trying to expand the tunnel. Fortunately, no one seems to have been hurt, but you guys are stuck there until we can get some support set up. Are you guys getting any air down there?"

EA opens their mouth to respond but Kobayakawa leans in first, almost a lurch. "Ah, yeah! This is Soapboy, reporting in. There's some air coming in some holes from farther down the tunnel, but it doesn't look like there's any light. Y'know, other than Hiei."

With his face in closer, EA can see that there's something off with Kobayakawa. His pupils are too small for such low light and he's sweating.

"Any injuries?"

"I must have been knocked out, but I'm fine. Don't even have a headache. Soapboy?"

"Well, we both got a faceful of the glowy moss when the tunnel collapsed; I think that might have knocked us out because I fell asleep too." His breathing is off, too, much more audible in the underground tunnel.

"You sure you're not hurt, Ellen? When's my birthday?"

"March 12th, Taylor. I'm fine, really." EA took advantage of the lull to create an orb of light, giving the cave a warm light, like a campfire.

"...Well, I'll take it for now. When you guys get out of there you're going in for a physical, you hear me?"

"Yeah, yeah."

Taylor pauses. "Glowy moss?"

Kobayakawa leans in again, shuffling awkwardly. "Yes. It's growing on the walls in here. It's blue and has a bit of light coming off it."

"Huh. I'll get try and find out what that is. In the meantime, any effects from the moss? Allergic reactions? Hallucinations?"

There's an awkward noise from Kobayakawa. EA looks up, but he turns his whole body away quickly. "...I'm fine." they say. "It's just itchy. I'm taking a shower when I get out of here; I can feel the spores in my hair. But…"

"But what?"

"Are you feeling okay, Kobayakawa?"

This time he turns to look at them at his name, like a dog. EA stared for a moment. "...uh… you okay?"

There was a very obvious bulge in his loose pants. "I- I feel, uh, weird." He paused a moment, before realizing that the magical guardian hero had noticed his erection. He quickly attempted to cover it with a hand.

"...Taylor, have you been able to find anything about the moss?"

Taylor replied quickly. "I'm working on it. Can you tell me, what color is the moss? And is the light coming from the spores, or the actual moss?"

"The moss is grayish. It's the actual moss that's glowing, blue."

There's a rustle from Taylor's end of the radio. "I think I found it. Schistostega peneta… an extremely rare moss native to Japan, China, and the Philippines. It's not poisonous or hallucinogenic, thank goodness. Oh…" There's a pause. "Um…"

"What is it?"

"It's- it's, uh, a powerful aphrodisiac."

EA paused. Awkwardly, they lifted the radio back to their mouth. "Well, that explains that… Kobayakawa is having a… reaction to it."

"...ghrk" There's a strangled sound that undoubtedly is a product of Taylor's mortal embarrassment. "... Ellen. Uh…"

"What is it?"

"The only way to detox peneta spores is through… orgasm. Ellen, it's going to be at least three hours before we can get to you guys… but if you're uncomfortable, I can see if-!"

EA cut Taylor off. "I'm fine, Tay. So…" They search for words. "I just need to have Kobayakawa jerk off, right?"

"...Yeah. It might take a few times. The, uh, article on it says that the moss doesn't really have damaging effects by itself, but the prolonged, uh, arousal will quickly become painful if left, uh, untreated, and more than an hour without, uh, relief, can cause permanent damage… you said you're fine, right?"

"Yeah. You know I chose Ace as my hero name for a reason, no?"

"Just, uh watch yourself."

"I'll be fine. Um…" They suddenly lose their confident hero persona for a moment. Ellen-Andrew switched to English. "Is it okay with you? I feel like I'm cheating, a little… things might end up-"

"Ellen." Taylor's voice cut them off. "You don't need to worry about that. You're fine with me and Anthony. We're friends, partners, and this isn't going to change that. Don't do anything that you'll regret and stay safe, okay?"

EA took a deep breath. "Alright."

"I'll be here if you need me. All you have to do is call… I love you, alright?"

"I love you, too, Taylor."

EA gently shut off the radio and turned to Kobayakawa, who had huddled in a slav squat against the far wall. "Did you get all that?"

He makes a sound before he nods roughly.

"Here, I'll turn around and hum if it'll help. I assume you can, uh, deal with it?"

Kobayakawa nods again, his face a bright red.

"Let me know when you're done or if it feels like it's getting worse." By now, their face is solid crimson, too, but they keep their professional face on as they turn to face the wall. Behind them, Kobayakawa's pants rustle loudly as they fall to the floor. There's a slight twang of elastic as the bubble hero's boxers slide down, then some low grunting. A pause.



"Um… do you have any lotion?"

EA's face burns again as they carefully pull a small bottle out of the left lower pocket on their cargo shorts. "Will sunscreen work?"

"Yeah." Kobayakawa's voice is curt. He's plainly becoming desperate.

EA carefully throws the bottle over their shoulder towards his voice. The cap pops open and there's a quiet squishy noise before Kobayakawa… resumes. His breathing becomes a staccato pant before he makes a muffled cry. EA stops humming and is about to carefully turn around when the sound of hand on flesh starts up again, faster this time. It seems like hardly two minutes have passed before there's another cry of release, this time with something almost like anguish under it.

Fuck it. Ellen-Andrew turns around. Kobayakawa stands in the dim light, underlit by the orb EA had created. His dick is still hard, looking almost painfully so. His eyes shine with what EA is taken back to realize are the start of tears.

"Are you doing okay, Koba- Ken?"

He opens his mouth but no words come out, only something that sounds like a desperate sob. "It hurts, a lot, Hiei, and it only helps a little, and I can't think straight-"

EA steels themself. "Ken. Can you tell me where we are?"

Kobayakawa is confused, but replies after a moment of thought. "We're in the tunnels…"

"Good. Now…" EA takes a careful step forward. "Would it help if I…" they trail off.

Ken's face flushes, but he starts to nod before he blurts "But, Hiei! You don't have to- I don't want to make you-"

"You aren't making me do anything, okay? And I don't like you like that, you know that. But you're my friend, and you're in pain, and I want you to be safe. So, if you want it, I want to help you."

"Then- please."

The note of distress in Kobayakawa's voice spurs EA on. They carefully bend down to grab the bottle of sunscreen and pour a dollop in their palm, spreading it to warm it. "If I hear anything like 'Stop' at all, I will stop immediately. If you can't get the words, tap me twice. Can you repeat that for me?"

"Hiei, I'm-"

They give him a level stare. "Repeat it."

Ken mumbled the instructions back at them, a slight slur turning his sibilants into 'sh' sounds.

"Good boy." They carefully wrapped a hand around his hot cock. "Let me know if you like something." EA ran an even stroke down the velvety flesh before pulling it back up. They ran their thumb over the slit at the head of the penis. Kobayakawa gave a startled moan and EA repeated their motion before returning to a swift, steady pattern of strokes. Moments later, his cock pulsed. EA stopped "Was that…?" They started to remove their hand before Ken stopped them.

"Hn- ah, don't stop. It-it's still not over."

EA returned to their stroking, mixed with gentle exploration of the glans and the veins on the sides. Kobayakawa came twice more, still dry, before he tapped their arm.

"It isn't working." he panted. Sweat glistened on his face. The constant arousal and orgasms had been draining on him; he was obviously exhausted.

"I'm not going to give up yet. It's been taking a little longer each time and you're a lot more coherent… I have an idea… if it's okay with you."

"What is it?"

"Use your bubbles to get the sunscreen off your… you know."

Confused, he complied.

EA took a deep breath before they carefully kneeled down. "Alright, same rules as before. And don't pull my hair." They opened their mouth and cautiously took the tip of Kobayakawa's dick into their mouth. He bucked at the sensation, gagging EA. They pulled off with a pop. "Don't move!" They gripped the bubble hero's hips firmly before sucking his member back into their mouth. They hesitantly tried to take more in, but left off when their gag reflex twitched.

Kobayakawa's hands rested gently in their short hair, tangling with the ribbons.

Overall, they found, giving a blowjob was interesting but somewhat uncomfortable. Ken's penis, cleaned thoroughly by his bubble technique, didn't taste of anything. It was almost like licking the back of their hand, but warmer. They hummed gently and prodded under the head with their tongue. They had seen it in the occasional porn videos they watched out of curiosity, and judging from Kobayakawa's reaction it was indeed something guys liked. They repeated the humming before cutting themself off.

Ken was definitely pulling their hair now.

"What did I say, Ken?"

Ken pulled his hands away from their head. "Uh, sorry, I couldn't help myself..."

"Well, if you can't stop, I'll stop you. Put your hands behind your back."

Kobayakawa complied. EA formed a simple light construct in the shape of a band, carefully securing his hands behind his back. "Will this help?"

He nodded.

A few minutes of careful licking and suckling passed before a now almost familiar pulse, accompanied by a soft gasp, proved that EA's experiment had worked. "Huh, I wouldn't have guessed you were into bondage." they teased, releasing Kobayakawa's hands. "It seems like it's definitely wearing off. How are you holding up?"

"Better. It barely hurts, and I can think clearly again. But I think I still have some moss stuff in my system." His dick evidenced this- still hard.

"Well, I don't really want to do that again anytime soon- no offense, I mostly wanted to see what it was like." EA paused. "There's one more thing I want to try, if you want to."

"What is it?"

EA carefully pulled their skirt down and stepped out of it.

"Wait! I, uh, don't have a condom, and-"

"Deep breaths, Ken. I want you to try fucking my thighs. I'm not even going to take off my underwear. How does that sound?"

He gaped like a fish for a moment before he nodded, enthusiastically. He bent over to gather the sunblock bottle before he paused. "Um, I know this is sort of weird, but… thank you, Hiei. I know you don't really like this sort of stuff, or guys in general, or girls for that matter-"

"It's fine, Ken. You're my friend and I don't want you to get hurt. And I'll admit, now that you're doing better, I'm using this to indulge some of my own curiosity. When will I get a better chance to try this, with no feelings attached?"

EA finished untucking the shirt part of their costume and undid the button fly of their cargo shorts. They laid the discarded clothes on the floor. "I'm going to lie on my stomach. You can lotion up my thighs. If I say 'Stop' for anything, we'll stop, alright?"

Ken nodded, repeating the instructions obediently and eagerly. He poured the remaining contents of the sunscreen bottle into his hands and gently spreading it into EA's thighs, avoiding touching their underwear or genitalia.

"That feels good. You ready?"

Kobayakawa made a noise of agreement and carefully climbed over the prone enby's thick thighs. He made an experimental thrust and moaned softly at the sensation. EA hmmed.

The now ironically named hero set a pace of thrusts, slow at first before becoming a steady pattern. EA remained quiet underneath him, save the occasional stifled giggle when an errant thrust hit a ticklish spot. The sensation of their thighs was pleasant, tight and warm. Ken's orgasm built up at a pace that was about normal, and his thrusts stuttered as the orgasm hit him. He rolled off of EA, suddenly exhausted. His pupils, now able to dilate, made the previously dark tunnel almost as bright as day.

"Looks like that was it, Ken." they said, glancing clinically at his now softening cock.

"Was that, uh, was that good for you? Do you want… anything?" he panted.

"It was interesting. I didn't get off, but I didn't really want that." They paused. "So you feel better?"

"Yeah. I think it's out of my system now."

"That's good. We still have probably an hour or two until they get us out of here, so you should probably take a nap. You look like you just ran a marathon."

EA watched as Kobayakawa wiped the sweat off of his forehead and nodded tiredly. He sat up and pulled his boxers and pants back up.

"Wake me up when you hear them coming, okay?"

They nodded, before they paused.

"...But before you go to sleep, could you get the sunscreen off my thighs?"

Schistostega peneta is based off of Schistostega pennata, an actual bio-luminescent moss that is in fact native to most of East Asia, Europe, and North America. EA doesn't get affected because they are asexual and have basically no libido anyways.
I note that Ken's hero name is sort of ironic, because a Soap Girl (or, more rarely, Soap Boy) is a type of sex worker who provides intercrural sex at bathhouses. I made this his hero name both because of his bubbles and because Jo2uke's stand is named 'Soft & Wet' and I wanted to get the innuendo bit in there. And lo and behold, he does indeed have intercrural sex with EA.
There's not a ton of it, but I did try to get a little bit of dom/sub stuff with EA and Ken because I find that sort of stuff interesting.