Ren has to wonder if he might have been stopped by his grandfather. The man is very likely powerful enough to have done it, but he had been preoccupied with his master at the time, it seemed. With he and Obi-Wan preoccupied, and Luke having yet to gain the sort of mastery over the Force that he had, that left Rey... who was killed because she believed herself successful too soon. She had let her guard down...

The tired man rests his face against his hand.

"It's lucky that he was there to do so."

Ren wasn't stopped until all the obelisks were lit, and he simply collapsed at that point. No one had been able to exorcise the phantom from his body. He wonders if it might have been possible at all.