The Brave and the Bold, Vol. 1

After being repeatedly attacked by people close to him who immediately suffer amnesia, Batman realizes he's actually being attacked by his former ally, Deadman. He also deduces that Deadman doesn't really want to kill him, as he always attacked with third parties that Batman could best, and not by possessing Batman himself and choosing a suicidal act. Realizing that Deadman had been brainwashed, they go collect his brother Cleveland's body to help them make the trek back to the temple where Deadman studies. When there, Deadman becomes corporeal again, only to find that the same drug that opened him up to brainwashing is also poisoning him. Batman and Cleveland then work together to find and defeat the group of criminals that were trying to use Deadman to invade the temple. Taking the antidote from one of them, they manage to cure Deadman before it's too late.