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"Derek and Callie become very good friends," Shonda Rhimes reveals. "When we come back they spent a lot of time together in the intervening months."
On the surface that pairing seems random, but when we think about it, it actually makes a fair amount of sense. For one thing, Derek and Callie are two of Mark's closest friends, so it's very possible that they bond over his injuries and/or death after the plane crash.
On top of that, we know Derek's hand has been seriously injured in the crash. It's possible that Callie operates on him, and they bond has she helps him try to recover.
Why do you think these two become friends? Let us know in the comments below.