They will come to collect at some point..and the cost will probably be high. I've already seen the darkness that lies below with the twins.

[He shuts his eyes briefly and takes a calming breath. The trauma of that day still haunts him.]

But I want to make sure before I leave again that I will remember. I want to remember you and the ones from your world and all the good people from the other worlds. And I want to remember this place so that if anyone goes missing again, we have a way to get them out and back home...and I have a way to get back to you and do all the things on your world that we planned.