You met Alastor somewhere rather sketchy, hearing that he can grant a great for you in exchange for possibly your soul. Once you met up with him, you told him a desire you wished to have, and his signature smile got more wicked.

Alastor: Ah, I see my dear... I can possibly make that desire a reality. In return I require something in exchange. So... Do we have a deal?

He held his hand out, green light and green power instantly surrounding his hand