Shell Bell doesn't get off the train immediately when they hit District Three. Tony has one last miserable speech to deliver, and the train will then stick around long enough for everything to be unloaded. Bell sits tight in Sherlock's compartment with the TV on, keeps her wits about her, and awaits cues from either Stark twin.
When she can smell food, she follows her nose to where she has learned the kitchen to be.
"Sherlock is making risotto," reports Bell. "It'll be ready soonish. How are things going with your swag?"
"This generator and I are going to be very good friends," he says. "I'll be up in a few minutes; you guys can get started without me if you want."
"Okay. Also we have something fantastically awkward to tell you and I wound up with the job of issuing the speech but I think I'd rather say it with her in the room."
"...What, did you have sex or something...? Never mind, if you wanna tell me when she's there, tell me when she's there."
She is very glad that they didn't, because having Tony guess right that casually would have been mortifying.
Bell sits at the kitchen table and fidgets and says, "He'll be up in a few minutes and says we can start without him."
"I told him we had something awkward to tell him but that I'd rather say it with you in the room and he just offhandedly guessed that we had sex," Bell says. "I told him that wasn't it."
Bell takes down three plates, and finds glasses too and sets those out. All the while she appreciatively sniffs the air.
"This is really good," sighs Bell ecstatically. Not even four months of non-potatoes from Bar has desensitized her.