It happens during their first hand-to-hand training.
“You’ll fight in pairs for about five minutes.” their sleep-deprived teacher mumbles in his usual bored drawl, “One will try to land as many hits as possible on the other. You don’t need to hurt them, just make contact. Also, I’ll erase your quirks randomly, so improvise and be quick on your feet.”
Mob hums, head tilting in thought. So speed and dodging skills were key here.
He feels his nervousness rise; his powers usually allow him to keep his opponents at a distance, but he wasn’t particularly fast or nimble by himself. Master Reigen did teach him self-defense, but that was all about contact and using the opponent’s strength against them. It wouldn’t be of any help if he wasn’t supposed to make contact at all, or if the other kept running away. He’d never stand a chance against someone like Ojirou or Iida.
He steels his expression in calculated blankness as he watches Bakugou rushes Midoriya, dropping expletives and explosions alike as his green-haired rival evades him time and time again, screaming in frustration when professor Aizawa erases his quirk at the worst possible moments. The explosive teen ends up hitting him a few times in the end, the self-proclaimed “Bakusquad” comprised of Kirishima, Sero, Mina and Kaminari cheering him on all the while. Midoriya doesn’t seem too down about it when they both walk down the platform at Aizawa’s request for a debrief; if anything, he looks even more determined to outwit the blonde next time they go toe-to-toe, lips already moving a hundred miles a second to take apart and analyze Bakugou’s new moves.
Mob’s own lips stretch up ever so slightly; everyone is always giving their all, so he will as well.
“Kageyama and Kirishima, you’re up next. Kageyama, you do the dodging.” their teacher announces, after letting the two rivals back into the crowd, Katsuki glaring daggers into Deku’s back.
Shigeo takes a deep, grounding breath and nods, stepping up on the platform; his red-haired friend and occasional coach steps in at the opposite side, stretching his arms and legs with a shark-like, but good-natured smile. “C’mon Mob! Let’s show 'em how hard we’ve been training!”
“Ah… yes, Kirishima-kun! Let’s do our best.” the raven-haired asserts, slipping into much-practiced motions. One foot in front of the other, stance wide, body lowered. Keep your joints and muscles relaxed, but ready to move. Breathe in and out, don’t hold it.
You got this Mob.
His power hums to life as his Master’s words ring through his head like a mantra, familiar and comforting. He breathes in, his straight black bangs float slightly upwards as his gaze settles on his opponent, ten feet in front of him.
The second Aizawa gives the signal -a half-hearted “go or whatever”- Eijirou crosses his hardened arms in front of him and bolts, coming straight for him. Mob shifts on his feet, ready to jump out of the way with a telekinetic boost-
-and gasps, his stance faltering; his bangs fall flat against his forehead and his brown-red eyes widen, mouth opening on a silent oh. He barely registers Kirishima’s sprint coming to an abrupt halt a few feet from him. Dirt flies off under his feet as he stops, blinking in confusion.
True, Kageyama was pretty hard to read. But the redhead had spent enough time with his blank-faced classmate to be able to tell when something was off. And he looked so stiff all of a sudden. “Uh, Mob? You with us bro?”
Shigeo doesn’t respond, too focused on the fact that the hum, the pressure in his mind, the very thing he’d spent every minute of his life trying to keep in check... is gone.
It had become such a normal, constant thing he didn’t even realize it was here in the first place. But now it’s… not there anymore. Just, not there. It’s... silent. Is that what true silence feels like?
He slowly turns around to look at Aizawa, who stands a few meters away from the field. His messy black hair is floating up, his scarf waving in an invisible current around his high-strung frame. His blood-red eyes are boring into him. Keeping his power at bay.
It slowly dawns on Mob: Eraserhead is erasing his quirk. For the first time in his life, his power’s been stripped away from him. Not for long of course, he knows this; it’s only suppressed for now, still here but just out of reach. But with this realization comes another one, and then another. He doesn’t see his classmates give each other confused looks, can’t hear them inquire him of his well-being or admonish him, snapping at him to get off his ass and move already, bowl-for-brains -although that last one is most likely from Bakugou.
He can’t lose control like this. He can’t hurt anyone like this.
I can’t hurt anyone.
He looks down at his hands, closing and opening his fists, reveling in the absence of burning-freezing pinpricks up and down his arms. Processing.
“Mob…?” Eijirou calls out, arm reaching out to his friend hesitantly. Shigeo’s eyes are hidden behind the dark curtain of his hair, soft tremors shaking his petite frame. There’s something inherently wrong about the sounds that are escaping Mob’s mouth, eerie and unfamiliar. Nervous whispers and a quiet, worried ribbit are the only things breaking the heavy silence that settled on the training grounds.
And then Mob’s whole body arches backwards, his raven hair flying as he laughs.
It’s not even that loud, really. It’s a broken, high-pitched little thing, wild and desperate and not quite right, like the teen’s chest and throat and face are not used to the frantic spasms that run through them; and the thought that they really, truly aren’t is too crushing to consider.
They watch, too stunned to move or speak, as Mob’s legs almost give out from under him and he lurches forward in an attempt to keep his balance; his features lost all that careful, oh so careful blankness they all grew to know and, for some of them, decipher. They’re almost unrecognizable now, stretched in ways that would make sense on anybody else’s face but seem weird and unnatural on his.
But it shouldn't be. Watching someone loosen up and express their feeling openly shouldn’t feel so…daunting? Solemn? Important?
And yet, they can’t help the feeling of pure uncanniness washing over them as they witness their friend’s hysteria.
Shigeo is doubling over now, arms holding his midsection. His laughter, while still manic, is shifting into something more fragile and soft. His pupils are blown wide and shining with unshed tears, eyelids almost forced shut by the huge grin stretching his pale lips. His nose is scrunched up, and dimples appeared around the corners of his mouth.
Mob has dimples when he laughs. That concept feels surreal to them.
There is just so much in that expression, in that laugh.
Surprise. Wonder. Relief. Despair. Ecstasy.
It’s a marvel to hear and watch, but somehow incredibly sad as well.
And just like that, it’s over. Aizawa blinks, once, and his hair settles down on his tense shoulders as Mob falls silent and still. He slowly straightens up, right arm falling back into its default position, left arm reaching up to wipe the wetness on his round, still flushed cheeks.
Mob stares at the older man. His voice is as dull and steady as ever, his face back in its usual neutral state, but his sienna eyes are shining almost feverishly.
“Please do that again.”