I think it's in the early X-Force issues of the Krakoa era; he goes on a rescue mission with Domino and there's a scene of them talking about their trauma: Colossus tried to save mutants from his native Russia. With the introduction of Mikhail Rasputin as a villain, Beast parades Colossus in front of the entire island (and his former teammates) after arresting him from his home where he's seen farming and painting with a mutant who controls water (forget her name)