Grey's Anatomy has a way of throwing a major wrench in the works every time a character's life finally seems to be going smoothly. Does that mean Derek — who's basically winning at everything these days — could run into trouble during the upcoming mid-season finale (Season 10 Episode 12)? Based on the synopsis for the episode, he's definitely going to face a major change tomorrow night.

The synopsis teases that Derek “gets a phone call that will change his life," which is disturbingly vague but also deeply intriguing. What could the call be? The possible answers seem endless, but that doesn't mean we don't have a few theories we want to throw out there.

Here are three life changing events we think could be headed Derek's way. After you read our ideas, we want to hear all about your theories, so speculate away in the comments below!

A big research or job offer. Derek has been pretty focused on his research lately, so we wouldn't be shocked if the life-changing call was related to his career. Since we doubt it would be solely good news (this is Grey's, nothing good comes without a price), maybe someone offers him more funding if he relocates, or he’s offered a new job elsewhere because he's being so innovative. Sure, Grey's has done relocation drama before, but they might find a new way to spin it.

A death in the family. Perhaps Derek's mom — or even one of his sister — passes. Anything that brings his family together is a setup for lots of drama.

Addison is coming back! OK, this is more wishful thinking than anything else, but maybe Derek finds out Addison is coming back to town. Because that would just be awesome.

What do you think the phone call will be? Sound off in the comments below!

Catch the episode on Thursday, December 12, 2013 at 9 p.m. ET/PT on ABC.

Rebecca Martin is an Associate Editor at Wetpaint Entertainment and our resident Game of Thrones, Breaking Bad, and genre TV expert. Follow her on Twitter and Google+!

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