Callie pipes up that he was blindsided by someone he trusted. There's no heavy-handed music here so it's being played for comedy, which is why I can't get too worked up about Arizona's great deception of not giving Callie a list of all of her hookups. Mark finally bites, and asks Callie what she said to Arizona; Callie still feigns nonchalance and says that she just asked how many people she had hooked up with and she's fine with the "one or two" answer. Even wise Richard can't keep quiet at that, and he clears his throat. Mark tries to stop him but Callie wants to know what he thinks and Richard reminds her that when a patient tells you they only have one to two drinks per week, a doctor knows to round up from there. Well of course -- because one sounds like a lush otherwise but a glass of wine an evening is not a ridiculous amount of drinking! Ahem. Anyhoo, his point is that people will tell doctors what they want to hear, and Callie realizes this means Arizona had far more than one or two drinks in the time before she and Callie got together. Just then Avery says he feels something sharp and while it seemed like an excuse to distract Callie, he then pulls out a tooth larger than my thumb. Richard is in awe and won't let Jackson toss it away; he tells a nurse to keep it safe.
Teddy goes to the waiting room to talk to Emma, who is trying to send her grandkids a picture of the lion. Teddy helps her out and in doing so, sees from the photo just how crazy close they got. Emma is very proud and tells her that if Martin faced a lion and made it, that means it isn't his time to go. She then asks Teddy not to make her a widow. Teddy is still trying to avoid that word and instead assures Emma that she's is very good at her job and doesn't want her to worry. Oh Martin, because I've seen TV before, I can tell you that none of this sounds good for you.
In the ER, Lexie is starting to do the surgery under Derek's watchful eye but then he realizes he just isn't comfortable and takes over the procedure, though he profusely apologizes. Lexie is clearly hurt but assures him it is fine. He seems to feel bad at this show of no faith and so after a moment he tells her that he's not going to tell Mark what to do. Lexie is surprised but keeps her replies measured and even, like Derek is an animal that could be easily spooked and run away from the conversation she wants to badly. He announces that he knows Mark well enough to know he'll move in with Julia no matter what Derek says, unless... he knew he still had a shot with Lexie. She's blown away by this revelation but Derek adds a stern warning: Mark is happy and that Lexie better be sure she wants him back because she loves him and not just because he's with someone else. Wow, that is actually good advice. Who knew he had that in him?