do you have any other headcanons for Iwaizumi with tics?
Absolutely! I have so many different headcannons for characters with tics since I personally do have them (main five being: Tendou, Oikawa, Iwaizumi, Kunimi and Kageyama)
Note: this doesn't touch on regression a lot, it's briefly mentioned at the end though :]]
Iwaizumi tends to mainly get tics from repetition, which he kind of finds annoying since his life does involve a lot of repetition.
He mainly has motor tics, he thought that it'd be a problem since he's a spiker in volleyball but since he gets so focused on the game his mind kind of forgets about it for the time being before hitting him full force after games.
He tries to suppress his tics during school which his friends aren't that fond since it usually makes them worse.
Hitting the back of his neck
Slamming his hands down on the nearest surface (if there isn't one he'll hit his thighs)
Neck twitches (it's typically followed with a click of his tongue)
He'll scrunch up his face and bite the inside of his cheek
Just yelling "Kawa!" it's scared a few people and he's nearly done it during tests a few times
"Nope, nope, nope!" Repeatedly
"Low budget!" (Came from making fun of bad movies with Oikawa)
"Come on!" Followed by him shifting his balance and rolling his eyes
Jazz hands followed by a sarcastic "Wow, so cool."
"0/10 no dragons." Then making a thumbs down and pouting
His tics get worse when he regresses plus some others are added to the mix
Usual regression tics are:
"Rawr!" Then bites whatever is closest or nothing
"To'ru no!" Then swats at whatever is near him