I also think this is about somebody returning to his/her family ("You're family, you belong to us"). And it could well be somebody who goes home after college. But I also listened to it as somebody who goes to see his/her parents/family with Christmas ("I think your darkest day should have some light this year"). His (girl)friend does not want him/her to go, because his/her family is not very supportive - actually, they're abusive... But this person does go home every year - after all, it is Christmas... So every year they put him/her down. His/her fire, his/her soul gets hurt. And the singer of this song can not sit back and watch this happen anymore...
I also think this is about somebody returning to his/her family ("You're family, you belong to us"). And it could well be somebody who goes home after college. But I also listened to it as somebody who goes to see his/her parents/family with Christmas ("I think your darkest day should have some light this year"). His (girl)friend does not want him/her to go, because his/her family is not very supportive - actually, they're abusive... But this person does go home every year - after all, it is Christmas... So every year they put him/her down. His/her fire, his/her soul gets hurt. And the singer of this song can not sit back and watch this happen anymore...