These characters were a bizarre as hell family. Half the time they’d try to kill each other instead of even bothering completing a mission. Much like in real life, you can love your family so much at times and still want to kill them. No family is perfect, we all have our demons.
Thunderbolts was a comic about former villains pretending to be heroes but in that book redemption was a huge part of the storyline. Thunderbolts is not the same comic it started out as but is still a good read if you want to follow the villains rather than the nobler heroes.
The Joker had his own series during the 1970s in which he faced off against a variety of both superheroes and super villains - which makes sense because we all know the Joker doesn't play well with others, especially other bad guys. The concept never really caught on because we never learned anything about the Joker except that he was the same murderous troublemaker he had always been. Although he was the protagonist of the series, certain issues feature just as much murder as those wherein he was the antagonist; of the nine issues, he commits murder in seven.
The character was one note and there was little in the way of character development. It was hard to root for a character that just makes random chaos for chaos' sake. He didn't grow, he didn't change and I think that is why the series failed. The Joker really only works when he is fighting Batman. That relationship needed to be front and centre in this series but the confrontation with the Dark Knight never happened and the title was cancelled after only nine issues.