replenisher

Punisher/Batman: Deadly Knights with Bruce saving Joker's life when Punisher tries to kill him, and the famous "Joker. Run."

Spider-Man & Batman: Disordered Minds with Joker saving Batman's life when Carnage nearly kills him because "It's my town-- and my Batman!"

Batman/Teenage Mutant Ninja Turtles III with Joker fusing with the crossover villain but Batman trying to save him and dramatically going "Joker. You need to remember who you are, you just need to take my hand, and you'll remember your old life. [...] Joker! Take my hand!" On a bridge, no less. Re-enacting their first ever meeting when Joker was Red Hood.

Batman/Shadow with Batman jumping in front of a bullet to save Joker's life while screaming "No!" but Joker still gets shot in the shoulder. Of course, he ends up in Batman's arms croaking out "You do care," while Batman snaps at him to "Shut up." Aww.

DC/RWBY with Joker fusing with the crossover villain and then Batman also merging with a villain but then the day getting saved by Ruby getting Joker to think he killed Batman, and to get Batman to think he killed her, in order to make them snap out of it and stop them. All while this parallel between a Remnant fairytale and Batman and Joker's relationship is hammered in, a comparison that lives in my brain rent free: "Gotham was a city of eternal night, guarded by a lonely, orphaned prince. There was a beast within the city. And whenever the prince slew one of its heads, two more grew in its place. But it grew so huge... the city itself was carried upon its back. And if the prince were to slay it, the city would fall. Yet, if the beast were to eat him, it would cease to grow, and would wither and crumble underneath the weight of the city. They needed one another."

Batman/Dylan Dog with Joker summoning Smilex because he wants to have a friend who's similar to him, but Batman going through hell and back (literally) to drag Joker's ass back to Gotham, back to Arkham, and telling Dylan Dog that "Monsters don't exist... They're just people who've had a bad day."

And now! Most recently, Marvel/DC: Deadpool/Batman with Joker summoning Deadpool because he wants a friend who's similar to him, and Batman managing to stop Joker's plan by making Joker jealous, which drives a wedge between him and Deadpool. This issue made it painfully clear that Bruce knows Joker very well, and how his feelings towards Batman work. He knows how to play them and make them work in his favor:

And if that wasn't insane enough: