While Batman stands for order and good in the world, the Joker is an agent of chaos. But there have been times when the Joker was good.
Yes, he frantically sows as much terror as possible as he attempts to prove that everyone is a monster on the inside. Where Batman demonstrates what people can be at their very best, the Joker is the exact opposite. He shows us what people can be when they lose their morality and instead act entirely on impulse.
All this hasn’t stopped the Joker from occasionally showing his human - and even virtuous - side, however. Whether it's a brief moment of realization of the things he's done, a complete shift in thinking that makes him a hero, or even a temporary partnership with Batman, good guy Joker does exist in the DC universe. You just have to dig deep into all of the plots to find him.
You might also be interested in this list of The Best Joker Storylines.
The events of Batman: White Knight see the Joker, here known as Jack Napier, cured from his insanity thanks to a new concoction of drugs. This renders the former villain relatively harmless, and he begins a new life as a council member in Gotham.
His main aim is to stop the corruption within the city’s police force and rein in Batman’s ability to act as a vigilante. The Joker even goes so far as to team up with Batman to fight against the Neo Joker, a new villain who wreaks havoc in Gotham.
Batman: Going Sane sees the Joker living a normal life. He takes on the moniker Joseph Kerr and gives up a life of crime for a seemingly happy existence. This happens when the Joker believes Batman is dead and he no longer has a nemesis to battle.
Only when the Dark Knight returns does the Joker return to insanity.
In The Dark Knight Returns, Batman gives up his crime-fighting ways, which drastically changes the Joker. Instead of being a master criminal, he accepts his imprisonment inside Arkham Asylum and doesn't attempt to escape or break the law.
Without his arch foe to battle, the villain enters a catatonic state and does not return to his old ways until Batman is back in Gotham.
Batman R.I.P. was a 2008 storyline in the main Batman comic series in which a group known as the Black Glove attempts to kill Batman and destroy everything he values. Members of the criminal organization invite the Joker into their plan, but he betrays them and actively works to thwart their plans.
As well as killing many of the Black Glove's members to stop them from carrying out their plans, he also encourages the organization's leaders to activate a transmitter that allows the League of Assassins, Nightwing, and Robin to capture them.