Life can be so cruel depending on what the dice roll may be. Most ponies get the good end of the stick as they gain their cutie marks for such extravagant and great things; but what happens to the bad end of that stick? It doesn't just disappear. Oh no. Someone else has to catch hell while others catch heaven. If it was all fun and dandy for everypony, the order of the world would be thrown out of wack.

Which is why he's here. To take up all that badness and hold it deep inside of him. Under careful watch of course. Because just as easily as he can take that darkness in, he can just as easily spread it and give it back.