It was the professor.

[Dimitri smiles to himself, though it's bittersweet.]

Even before coming here, I knew that I almost certainly would not have survived without them — now I know it without question. That person has the power to change fate. Did they teach the Blue Lions in your timeline, Felix? Or was it another house?

[A question he already knows the answer to, deep down, but he would like to hear it all the same.]