Brook Hale watched her Mom die.
She also was abused by her step father.
She runs away, thinking it would be best if she could be with her Mother.
On the other hand, One Direction need to think things through... on their favorite hideout on the top of a building (don't worry, they're not suicidal).
Brook Hale goes on the same building to jump, but they go up at the same time.
They manage to take her down, and bring them to Louis's house.
Eventually, they have to take her to the hospital again, and when they realize she has depression and its her final days, they do they're best to keep her happy.