[...A very powerful siphon. Which might, ultimately, be the key. It's worth noting, though not remarking on. She's upset enough. Better to focus on...

Well. That question's not much better.]

Comstock is dead in one world. But in a million others, he is alive, and... his actions continue.

Your powers, fully realised, can conquer time itself. So it's merely a question of choosing the right door to allow you or Mister DeWitt to stop him from ever being a threat to anyone.

[And is the better word, but he can lie. Make it sound like she has a choice.]