just a thought ...
have you ever picked him up regardless of his behavior ... and held up him gently but firmly up against your chest?
if you need to use gloves, use gloves. i might have missed that somewhere when i was reading your post.
it *seems* like you can sometimes redirect aggresive behavior by simply not allowing it to happen if you have the time or youre not too apprehensive to work on it.
remember, you're the one in control, but he is now pretty much controlling you. you can close his mouth, just shut it and hold it, like hahahaha no way Cartmen, no way.
and hold his tail still too. see if he stops fighting and resisting, until he tires out and calms down. he will tire out.
god, i know that must be so frustrating, escpecially since you raised him yourself!
you are right, some dragons just are aggressive in behavior, as some are chill, some are active, some are still, some are personable, some are curious, and some would just rather be alone, some thrive on being around people, and some are just NUTS ... it takes all kinds to make the dragon world go round.
generally though, it seems this kind of behavior comes out when the dragon is abused/provoked/neglected and scared (which Cartmen is NOT!!!) so i know this must be really difficult to deal with.
If you can, or if you havent already, try the holding method, consistently an d persistently. You dont wanna stress him out by doing this, BUT, Cartmen sounds like he is already really high strung, so the holding might eventually yield the opposite result, and calm him down. i would recommend the hand in the tank method, but sounds like he is going to go right for it to bite!!!
i wish i could be more helpful, but let me know your thoughts on this.
i remember when Blue was a baby, she would open her mouth at my hand, and i would just close her mouth, like, NOPE, and work slowly with her, she has become the most chill dragon ive ever encountered
If he sees Chimera, that can be a trigger to be on guard and aggressive. Chimera seems like a sweetheart. It seems like you have tried alot as far as placement of the tank and such, i would try not placing him to where he can see Chimera.
My dragons have their own rooms, but i know you have tried that as well.