Joker

"Well, that’s the question, isn’t it? Riddle me this – the less of them you have, the more one is worth."

- The Joker to Edward Nashton

The Joker was a patient of Arkham State Hospital locked away for an unknown crime. Presumably a former enemy of Batman, he is implied have been at the top of his glory unknown time ago but lost everything, ended viewing himself as a "clown".

In 2021, after the failure of Edward Nashton scheme of revenge over Gotham City, he meet him after the two were locked in adjoining cells. He so befriended him and asked him a partnership.

Personnality
"Isn’t that just terrible? Them raining on your parade like that? What is it they say? One day you’re on top, the next you’re a clown."

- The Joker to Edward Nashton

To complete

Facilities

 * Arkham State Hospital: To complete