out of all the ignis, i like to think that flame and ai are the cuddliest, with ai being the most cuddly and also the most absolutely inconvenient about it
i feel like he would just go full six limbed eldritch gremlin mode whenever he decides it's appropriate and wrap around like a clingy snake. Trying to do chores? Trying to go somewhere? Trying to speak to someone he decides is getting too much attention? You're losing your mobility privileges for the next hour and getting a head hanging over your shoulder either making snarky comments or cutting filthy one-eye-jagged-jaw looks (definitely not showing off) to anyone who looks in the general direction.
trying to stay focused? gonna have to learn to deal with 30 (hmm. i wonder what an ignis would weigh?) pounds of pure snark and nosiness hanging around you like a backpack and asking about every single move you make.
Trying to rest? look out for the giant purple shadow about to envolope you like a sentient heating blanket.
even worse if you're ticklish, because we all know he's a little shit (affectionate)
even in his soltis form i feel like he'd be the type to just sneak up unannounced behind and wrap his arms around you with half of his weight bearing down to scare you on purpose
although I think you'd end up with a stunned silence and a blush if you pat his head because deep down past the jokes and sarcasm he really actually does want that hug and just won't admit it.