Doctor Jeremiah Arkham sighed unhappily. It was that day of the week again.

It was the day when the Joker's fan mail came in.

With five security guards, Arkham went down with Head of Security Cash to where the mail was kept, and found that, since the madman's last escape and recapture almost a month ago, that the amount of fan mail he had been receiving had increased by 20%.

When the other inmates in Arkham Asylum heard of this, the reactions were mixed: Pamela Isley was outraged at how the Joker had somehow managed to 'manipulate' people into loving him, while Edward Nygma and Roman Sionis were both impressed by the fact that the Joker now seemed to possess his own private army.

His own private army. It was this thought that worried Doctor Arkham, Cash, the City Council, Commissioner Gordon, the Batman, and even the State Senate and Governor. The Joker had been around for the past twenty years now, and was around fifty now. But he was still somehow as fit and active as he had been when he had just sauntered into Gotham, which led a few deranged inmates to believe the clown was immortal.

They had so far counted up to 35,000 regular senders of fan mail to the Joker, a quarter of them being women aged between 18-35.

"The Joker has around 35,000 deluded regular senders of fan mail?!" called the Mayor one Monday morning when he and the Council asked about the content of the madman's fan letters, in case he ended up getting ideas.

"Yes, Your Honour, and they seem to worship him, and Harleen Quinzel too, as a result of her close affiliation to him. This is the exact reason why we should keep him alive and not give him the death penalty."

"We shoulda executed the bastard years ago," called out one Councilman. "He'd have killed 500 fewer people than he has now."

"Councilman Garcia, I understand your point, but the number of people who send him these letters….well, that's just those in the U.S….he pretty much has a cult/army around him. If he dies, they will more than likely try to honour his 'legacy' and come here and burn Gotham City to the ground, then use the gas on everybody. Think 50 of the Joker's petty-crook mercenaries are bad? Try dealing with 68,946 nuts from all around the world who love him obsessively, coming here and turning this place into a warzone, killing people the way he did. Also, suppose one of them has every single piece of his insanity and becomes Joker Jr…."

That shut them up, and Congress when the issue of his life came up. As it happens, nobody, not even the FBI wanted to deal with a cult-army of Joker followers, plus his usual army of around 500 henchmen and thugs.

So, it was decided, for the long-term safety of Gotham City, to keep the Joker in Arkham Asylum.

And that is why he's never been executed or killed by somebody.