The devil will grant power to a human for a certain period of time before devouring them.

A deal with the devil.

If you make a deal with me, I'll become your eyes.

Any sane individual wouldn't even consider the offer.

That's why the devil targets individuals who are at the lowest point of their life.

Correct.

I'll be able to see then, right?

I'll do it!

Then the deal is sealed. You have ten years.