Lucifer

Lucifer was just talking to Charlie, and the topic of their conversation turned to Alastor. Although Lucifer didn't want to talk about Alastor (at least due to their status as enemies with each other), this conversation was good for Lucifer. He learned that Alastor was afraid of dogs, as they were connected to his death. Lucifer began to think of his plan.
Alastor was calmly walking down the corridor, when suddenly Lucifer jumped out from around the corner in the form of a dog (since Lucifer can take the form of any living creature) with a piercing bark. Alastor jumped on the spot, and stepped back, pressing his ears and tucking his deer tail.

You are Alastor!

Lucifer wanted to scare Alastor, but it went too far..