Well, I have some-what of an idea but I just thought it up so I haven't gotten too in depth of the idea. So far I have thought up some enemies.
Crawlen, dead souls of those who have committed wrongful sins in their past life and seek to bring hate to the souls of the living and cause them to do the acts that forced the Crawlen to become what they are. Then those who sign up could be a group of Raiken, souls with mystic abilities who use them to track, and obliterate Crawlen. Raiken were originally created by Santa Clause as a way to keep the line of good and naughty children evened out, then souls found a new source of magical powers without being under Santa's rules, the Northern Pole; a mystical item that keeps the spirit of Christmas alive, without it, all living things would lose their will to be happy and would resort to hateful crimes. For now, very few Crawlen have been able to come close to the Pole, but those that have evolve in a different way than becoming a Raiken, instead, they become Sheriken. Sheriken are quiet similar to Raiken but have darker, more powerful abilities. Their activity was very weak for some time, but all of a sudden, Santa has felt their presence in the north. He has feared the worse and so he sends a group of Raiken (those who sign up) to locate and defeat this enemy.
btw: You all can do what you like with this idea if you find any interest in it.