Lets just get it out there right now, Nerio have a horrible personality with a shitty attitude with a awful temper how really gives no damn about others feelings. He can be really mean and rude and just a complete asshole to be honest. Despite his shitty personality though he is actually nicer if taking time to get to know him and they might even realise he is putting all of this up for show. Nerio have not been having a easy life, it's full of bedrayal and abuse so have put on this asshole mask to use it as a shield to protect himself from letting others hurting him. He is also the host of a fake demon how claims themself to be a demon and Nerio even believes they are. Thier name is Youkai and is residing inside of Nerio. Youkai is the only one Nerio really trust but is completely unaware this is a one sided friendship between the two since Youkai really dosen't give a shit about Nerio and is slowly eating Nerio's soul away from the inside. Pretty much Youkai is a parasite how lives by eating on thier host humanity and negative emotions until thier is nothing left of the Host anymore and so Youkai can make the body to his own.
Nerio is pretty much open for anything really, arguments,fights, trying to give him a chance and befriend him. Sleep buddies (he is gay ) or someone Nerio just gets clingy to and stick around with. Anything really, just know if Nerio actually start to like your character he will become clingy as fuck and just pick fights with anyone how is mean towards them.