Well really it's tough to find a season for them that isn't a bit twisted :P

And yep, season 6. I think that being on death row, and knowing that Beecher had this great new life, messed Keller up a fair bit. I know that originally the ending for Keller was supposed to be the season 4 farewell scene, but then CM asked to come back. But Keller spend most of the time in seasons 5 and 6 locked up, he couldn't even scheme with Ryan any more or share the pod with Beecher, it wasn't the same for him :/