My personal theory about Sombra right after watching the premiere was that he's Celestia and Luna's father. I mean, think about it... He was banished by the sisters 1000 years ago, but it had to be before Luna became Nightmare Moon, or else Luna wouldn't have been able to help. Wouldn't it make sense for such a parasitic villain as Sombra to possess his daughter from beyond the ice, to fill her head with bitterness and anger towards the stronger of the two sisters?
And doesn't Nightmare Moon bare a striking resemblance to the King? Her smokey magic, her eyes? And I can't get Luna's disapproving stare from the beginning of the episode out of my head. Was she bitter that Twilight was chosen to defeat her own father?
The answer to all this is... Probably not. But it's still fun to think about!
Regardless of theories, I wanted to draw drunk Sombra and Luna telling him to gtfo. I also wanted to take a stab at Sombra's articulate nature. Because ponies.