So biggest plot twist of all would be when Iida gets attacked by stain instead of going to kill him he says something like "Would you like to become a villian?" And Iida just goes "ya know what yes". So stain takes him and drops him off with the league to be a traitor.
Iida is the same at school except having come to some 'revelation' after being 'unable to save' Native in Hosu. As a villian he finds loopholes in laws and keeps track of his acts of villiany.
His choping motion is modified to add throwing knives while he does it as a villian.
Kurogiri loves him as hes still a big stickler for the rules and being on time. He can now take that to the extreme and follow up nonrule following with violence. Hes polite and uses his manners as a weapon of itself in conversation like a backhanded compliment.
Kurogiri is teaching him the art of passive aggressive conversations.
