What happened to Quinn and Colin?
Quinn and Colin were “melded” in a freak accident within the wormhole at the beginning of the 5th season, in an episode entitled “The Unstuck Man”, and they formed the character of Mallory. Mallory has the memories of both Quinn and Charlie. The scuttlebutt is that Jerry O’Connell wanted Executive Producer status on the show and the powers that be balked. He ended up leaving the show and without him, there wasn’t much of a reason for the producers to keep his brother Charlie.