Luke takes a moment to gather his thoughts, then speaks quietly. "I know I should be glad to know it. Maybe I can keep it from happening in this timeline, at least. But I wish I didn't know." He bites his lip. "Apparently I -- some version of me, anyway, in whichever version of my future he's from, went and got apprenticed to a clone of the Emperor. He didn't tell me any more than that. Not that I was exactly encouraging, but... he went quiet. Two-word sentences. I don't know what happened."

And I'm sure he implied I hurt Leia. More personally, more directly than the whole mess would have hurt her. But he doesn't want to bring that into it yet. Enough to worry about the broad-strokes future for a few minutes.