Falling angels sister (BBC Sherlock)

We all fall, every one of us. Weather it's by falling emotionally or physically. The Holmes family? Well... It's seams they have a habit of falling both ways. The youngest of them fell from a bridge at the age of 9, the other two brothers fell into deep depression, loosing their fun loving, childish personality to be replaced with a grown up, emotionless if not hateful attitude. Nothing, and nobody will fix their shattered hearts... Except... Maybe.... An angel?