If Rogue had set out to look for the complete antithesis to Gambit, she could not have found a more perfect candidate than Piotr Rasputin. Colossus was an idealist, a dreamer, with an almost child-like purity of heart and spirit. He trusted people completely. He hid nothing of himself or his history from his team-mates. Despite a brief defection to Magneto's acolytes, he had no doubts about his place in the X-Men. He was as transparent as he was straight-forward. That alone would be enough reason for Rogue to choose him for a rebound fling, which it clearly was, but he also could touch her in his armoured form as this scene from X-Men #100 shows quite... vividly:
COLOSSUS: You are miserable.
ROGUE: Happens sometimes.
COLOSSUS: I wish to help.
ROGUE: Then leave me alone!
COLOSSUS: Rogue, what you and Gambit had was special. Can you not give him another chance?
ROGUE: This ain't about chance, Petey, it's about choice! He's head of the Thieves' Guild. Suppose we cross swords, the Guild and the X-Men, where do his loyalties lie? Remy figures he can straddle those two horses, but sooner or later he'll have to ride one or t' other. He'll have to choose who t'betray. How d'you trust a man who can do that? How can you love him? It was his call, Peter. He knew what was at stake. Now we have t'live with the consequences.
COLOSSUS: I am truly sorry, Rogue.
ROGUE: Colossus, are you NUTS?! You touched me with your bare hand! Nothing happened.
COLOSSUS: Perhaps we should touch again... to make certain there is no stake.
Whether or not they had sex as a result of their discovery they could touch is debatable. On the one hand, unless Piotr has very little... stamina, they probably would not have had time to do so. Piotr visits Kitty immediately after the scene, then, later, is shown sketching Rogue in her quarters. On the other, they did have a rather telling conversation when the space-station was coming apart and shaking beneath their feet:
COLOSSUS: Was it something we did?
ROGUE: Cute. But if it was, Petey Pureheart, it was worth it.
Irrespective of that, it soon became clear that Rogue and Colossus had somewhat different expectations of their relationship. Rogue always saw it as a fling, while Piotr developed deeper, romantic feelings for her, as she discovered to her horror when she absorbed him to fight the Neo:
ROGUE: Want it or not, he's given me a window into his memories -- an' his feelings.You sweet, Siberian plowboy, this is a complication neither of us needs in our lives.
However,the implications of their relationship were never fully explored as it did not take Rogue and Gambit long to get back together again... .