Just checking,

If my opponent uses an effect to steal one of my characters, like for instace Grodd, and I then attack that same recently stolen character with Redshift, choosing t use his ability to remove them both from the game, at the start of the recover I would regain both characters, correct?

"Concealed
Cosmic: Whenever Red Shift attacks, you may remove all attackers and defenders from the game. If you do, put those cards into their owners' front rows at the start of the recovery phase this turn"

Edit: sorry, somehow I managed to put this in the wrong forum.

that is correct, it puts the cards into their owners front row. by deffinition, you own a card if you started the game with that card in your deck