Frost is like, "Yeah, he's sort of off the rez and is totally interested in taking on the CIA and this ridiculous Agency HQ and starting WWIII because of how he's in love with me?" They look askance at her, because does that mean she's evil or what, and she's like, "I could easily assuage that particular worry, but I'd rather stand around looking like the inside of my head is 100% that Johnny Cash cover of 'Hurt.'"
Alexei: "Are they treating you all right? Did they feed you? Was it good? You tell them they'd better continue treating you well or I'll make life very uncomfortable for them very soon... I'm not leaving here without you, my love!" That was the first but not the last time in this episode that my brother Lyle was like, "This is actually what this show is like?" Sometimes, buddy. Sometimes it is.
Chuck jumps to assumptions about how Frost left Steve for Alexei Volkoff and whatever, she's his supervillainess moll, and finally -- this is where you start to see it forming -- she literally goes, "Sarah, explain to him." (This again with the shared knowledge of the world that's denied to our hero; the reason it's a classic noir theme is because it's a classic boy theme, because boys actually think this way. Like there's a joke they're not in on, and the rest of us are. And they're not wrong.) So Sarah's like, "The world's biggest psychopath falls in love with you, and you're undercover with him?" Chuck gets it, with little prompting: That would make you a serious intelligence asset.
Sarah wonders why Frosty didn't just take Alexei out years ago, if that's all it is, but her mission is to take down the whole network, which is still a possibility apparently, if Castle turns her over to him. Or else they're handing over an enemy agent to her boss/BF with even more CIA secrets than usual. But this is the important bit, and you could miss it entirely if you weren't looking for it: "Chuck, going undercover for so long and staying loyal is an extremely hard thing to do as a spy, I mean... I got lucky. I was assigned to you. Your mom got Volkoff."
My emphasis, because that's how he'll get it back. There's nothing Frost knows that Chuck doesn't know, except that he is a better man than Alexei. That Sarah is lucky to have him, because they have fallen in love. And Frost never, ever would. One broken couple, one perfect couple. Moms are just people. So it solves the Frost/mommy issue at the same time it solves the Intersect problem and, obliquely, the larger blonde she-male problem, which were all already the same problem, which is why these three episodes exist. Three weeks ago I was pretty sure this was going to be my favorite non-Bryce storyline, because I hoped it would do this, and it did exactly this, and it did it well.