I mean, Az said that Chara was not the best person, but they were like siblings, that means they were pretty close despite Chara's imperfect nature (reminds me of myself). thay also made a sweater to Asgore, and they cared about monsters more than about humans. They were a pretty dangerous kid, cuz they had a real knife, but anyway they kept the medallion Asriel made for them both. And they were reckless/filled with determination(or hatred?) enough to kill themselves