One day, Dick gets hurt. It was inevitable; it's not that Dick is *more* careless than Tim - than Bruce ever was - but it's carelessness of a different kind. Tim knows, at a fundamental level, deeper than his bones, that in the large view his life doesn't matter. His purpose is service to his world, and hesitation in the face of evil is the greatest sin.
Dick knows, despite everything he's seen, that the universe is a kind place, and everything works out to a reasonable approximation for the best.
And one day, it nearly kills him.
Tim has business beyond the solar system, occasionally, and increasingly often as the Earth tentatively abuts the future. He finds an unaccompanied green lantern ring, a dozen light years away from his homeworld.
Tim immediately goes back to his planet and returns with Dick aboard his ship. Stabilizing him for hyperspace is complicated, but not impossible as bringing the ring to him would have been, five years out from the Disaster. Any lantern ring entering sector 2814 would have promptly destructed, taking with it the unfortunate wearer or, if applicable, the starship it was on.
Tim has seen the result before. He believes in being certain about failsafes.
"Tim," Dick says, after Tim has given Dick the ring. It is the first word he's said in a long time. "Tim," he says. "Don't make me choose."
Tim reaches out and grips Dick's hand. The fingers intertwined with his glow green.
"I won't," Tim promises. Tim has done it for him.