Simon Petrikov was a humble man, a good man. A cursed artifact saves him from death during the war, but at what cost? All he knows is that sometimes bad things happen to good people, but if it's the last thing he does, he will protect the ones he loves...and that includes from himself. AU

When a mysterious assassin threatens to kill off all the royalty in Ooo, Princess Bubblegum calls upon the services of a legendary knight to protect her kingdom. AU.