Tony hesitates for a moment, remembering thinking the same thing when he'd seen Gene with the tenth ring - that the ring does something to him, gets inside his head and messes with him. But that was back when Gene was still struggling with himself, before he'd proved himself a changed man over and over, before Tony had forgiven him.

"No you won't. You're different now. I trust you, Gene." He holds the ring closer. "Please, Gene. Can you... can you just try? I'll take it right back if you don't want to keep it."

He's practically begging. He can see that this is freaking Gene out, and part of him is getting really uneasy about the whole thing. But he's scared: scared of losing his memories, and losing Gene. He isn't thinking straight.