Not every hero in the DC Comics universe chose to be one. Sometimes events just shaped their lives. A perfect example would be Boston Brand. During his life, he was a world famous acrobat, known as the Deadman. Then one day a man who a hook for a hand shot and killed him for an unknown reason.
Now a spirit, Deadman roams the world looking for answers about his death, and the man with the hook for a hand. As a spirit, he can phase through objects, fly, and can possess people. Quite hany powers to have.
Depending the incarnation, he's also invisible to certain people. In both Batman Brave and the Bold and the Justice League Cartoon, only those trailer to see the spirit world could view him, else he had to possess someone and speak through them.
Deadman and Batman have had quite a relationship in the comics, in some continuities, Batman even seeks to help bring Deadman peace by finding the man that killed him. Batman trusts him because unlike other characters, there's honestly no malice or evil in Deadman, he's just a victim of circumstance.