I did some more thinking and I think I'll make Jado more of a jokester character. Usually the first one to make a joke or a silly remark. Sometimes even spouting out the occasional pun or stupid catchphrase! Like I said before, he can especially be seen giving a bit of friendly sass to Iida's serious mentality. Though he knows when to take things seriously, and in the end he's still a sweetheart who always looks out for his friends.
Also! His dorm would be filled with toys, figures and video games. Very kiddy, I know. But Jado is just the fun type!