Shadow Flames

Based on this prompt by Evangeline74 from AO3 (( http://archiveofourown.org/users/Evangeline74/profile )):
Years before he married Sharon Xavier Kurt Marko used to own a hotel. However he abandoned it after it burned down due to mysterious circumstances. Many years later, after Sharon's death, Marko has already squandered the entire Xavier fortune so the only thing worth of value now is the hotel. But to his son Cain's great rage Kurt refuses to give the property to him. Instead before he dies he leaves the hotel to his stepchildren as well as his son so the three now have to share it.
When they go to check out the property they're surprised to find it's already occupied and its residents were partying the night away. They join them and Charles gets really friendly with one of the guests ((aka he's seduced by him - that's Erik, people!)).
But things are not what they seem. The residents aren't what they seem either and soon Charles and Raven realize that their new friends are actually the people who died in the fire years ago...