"Don't— don't do anything before you're ready," Tony says, trying not to sound reluctant.

It's so hard not to listen to his reckless impulses - but if Gene can change his ways for Tony, then Tony can do the same for Gene. He won't rush this. He won't ask Gene to try it until he's ready.

"And I promise I won't go anywhere until then."

It's not a promise he has any power to uphold, but it won't be for lack of trying. If sheer stubbornness can tie him to this universe, they won't have anything to worry about.