You have more than enough prana that she would be quite satisfied and indebted to you afterward. It is how she feeds.

And try as she might, I will not give her so easily what she desires. But she is useful. That is the key, Rin.

[Saber chuckles.] You waste your time as is; there is always a superior alternative.

[Come on, Rin. Lancer? Pfft.]