Coal needed help if he had any hope of dealing with Xan. He thought over who he knew and whether or not they would be of any use.
There was Alex, a girl in one of classes who was an expert at shapeshifting spells. She knew how to cause specific physical changes to a person's body, without affecting their mind. However whilst she may be able to help if Coal changes physically, right now Coal needs some one who can help with mental changes.
To that end his best bet might be Matty. He knew how to prevent and reverse mental changes. However he's was in Coal's Demonology class. He'd be dealing with the side effects from his own potion. As such he may not be able to help.
Of course he could always go to Jordan. He has experience dealing with familiars. After all his own familiar Calibur is significantly more powerful than Xan. Maybe he could help with getting Xan back in line.
Coal's last bet was to go to his Demonology professor. He knew everything about demons. But if Coal went to him he could get into some serious trouble.