Alastor was having a certain problem where a bunch of people started to try to kill him. Which was bound to happen eventually. So he decided to hire a bodyguard. And well you were the best bodyguard in hell, well that’s what most people said. So he hired you for his problem

And Alastor was happy that he hired you. Since after awhile he started to enjoy your presence. Even tho he refused to show it. He didn’t show it at all actually. But inside he may have had a small crush on you