Credit: Adam Taylor/ABC Television Group © 2011 Disney Photo: Mark and Derek on Grey's Anatomy May 12, 2011

We've chronicled some of our favorite relationships of Grey's Anatomy, highlight by highlight, but here's a favorite of the favorites: Mark (Eric Dane) and Derek (Patrick Dempsey). These two are besties, though you'd probably never hear them admit it. However, this friendship hasn't always been smooth sailing. Normally, we don't focus on the bad times when reflecting on best moments, but in this case, the bad times are just too juicy to omit. Let's get crackin'.

The punch
What a way for a character to enter a show! Mark was barely a few pick-up lines into his flirtation with Meredith (Ellen Pompeo) when Derek's fist came flying into the picture and across Mark's jaw. Since we knew Derek wasn't the bystander-punching type, we assumed that he and this steamy newcomer had unfinished business. Turns out, that unfinished business's name starts with A and rhymes with Radisson.

The confession
At the start of Season 4, Mark ratcheted up the bromance level when he told Derek that he didn't come to Seattle to win back Addison, he came to win back Derek. He instantly regretted letting those words escape his mouth, and Derek didn't look like he was about to let Mark off easy. After all, aren't straight guys supposed to blurt out "No homo" after things like that?

The other punch
Mark and Derek's other epic confrontation came when Mark confessed to Derek that he had broken Derek's cardinal rule and slept with Little Grey, a.k.a. Lexie (Chyler Leigh). Honesty is the best policy? Yeah, try telling that to Derek's fists. The brawl left both dudes bloodied, but we all knew that they'd make up in the end.

The pep talk
And make up they did, in hardly any time at all. When Derek was discouraged by the red tape involved in an international adaption, Mark reassured him, admitting that he's been jealous of Derek his whole life — not just because of his hair but because of his sheer awesomeness.

The defense
At first, Mark was pissed that Derek stole Jackson (Jesse Williams) — his golden boy, his plastics protégé. But then Mark was pissed that Jackson seemed to just be using Derek to scrub in on more surgeries. "Nobody uses my boy," he said. See? Punches or no punches, Derek and Mark will always be each other's boys.

Remember to tune in to the next episode on Thursday, January 12, at 9 pm ET/PT on ABC.

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