Having cuffed the two of them by their hands and feet to pipes sticking out of the basement wall, their kidnapper decides Joan and Marcus are sufficiently detained that he can go collect the first half of their ransom. Joan finally gets herself to stop shaking once he leaves, which is good. More trembling at this point is gonna mess up her escape.
"Hey," Marcus says, getting her attention. "We're gonna be okay. You know that, right?"
She sighs, her voice quivering more than she'd like. "Yeah, I know." Usually the suspects don't bother her so much, but this guy - it hadn't even been the things he said. Just the way he looked at her creeped her out in the worst way. But now that he's gone, Joan can take her lock pick out of the lining of her bra and get to work breaking out of these things.
"What are you - " Marcus starts to say, his voice strangled, but before he can finish the question he must catch sight of the instrument she's working into the keyhole of the first pair of handcuffs. "You carry that around with you all the time?" he asks. Joan can't tell if his tone is more disturbed or impressed.
"Part of my studies," Joan says after the first cuff falls open. It's easier to get at the second pair with her hands free, so she doesn't have to concentrate as much on the task. "Sherlock can get out of a straitjacket in under five minutes. He expects I'll be able to match his time in three months."
"Man, I knew Holmes was ridiculous, but you are all kinds of incredible."
Touched, Joan stops her work on the last set of handcuffs for a moment. "Thank you."
"I'm only saying it 'cause it's true."
In the admiration on his face she finds the answer to a question she hadn't realized she was asking.
The second she's free, Joan cups his face in her hands and kisses him. After a moment of surprised slackness, he responds, gently, turning her desperate act into something calmer, more chaste. A minute - or two, or more - later she pulls back, tingling and breathless for reasons unrelated to exertion. Belatedly, she realizes that he's still chained up, and she sets herself to fixing that, ears burning.
"Sorry," she mumbles once she's gotten him loose. Marcus doesn't respond, rubbing at his wrists. The silence stretches too long, and she has to look up. He's watching her with a neutral expression on his face. She flushes. God, she hasn't felt this stupid over a guy since she was twelve. "I - I didn't mean to..." But she did mean, sudden as it is, and the lie catches in her throat.
Marcus doesn't say anything for a minute. "Whatever you did or didn't mean," he says carefully, "can we talk about it later? Only, I think your partner - " Oh no, please don't let him mean - but yes, there's Sherlock standing at the top of the stairs, frantic worry and relief and voyeuristic curiosity battling for dominance of his expression. " - would like to have a word with you first." Climbing the stairs, he adds, "And I need to call this in. Unless you already did that?" he asks Sherlock, who shakes his head. "Right. Couldn't distract yourself from finding us by alerting the authorities."
"He - " Sherlock's voice breaks; he swallows, starts again. "The kidnapper said no police."
"Of course he did," Marcus sighs, heading off in search of his phone.
Leaving Joan and Sherlock alone.
"Uh... hi." Joan holds up the lock pick, smiling. "I finally got to put this to good use."
Sherlock doesn't take the hint. "Are you and Detective Bell involved now?"
Joan throws up her hands. "Why am I surprised you went for the topic I wanted to avoid?" she mutters. Sighing, she climbs the stairs until she and Sherlock are face to face.
He watches her expectantly. "I haven't heard an answer."
"Well, I don't have one, okay?" She walks past him, remembers that Marcus is out there, and turns around again. "Things are a little uncertain here," she whispers. "I didn't even realize I liked him until just now."
Taken aback, Sherlock frowns at Joan. "Really?"
"And don't - " Joan waves a hand in his face. "Don't tell me that you saw it coming eons ago, or whatever. I don't need to hear that."
"On the contrary, Watson, I'm as surprised by this development as you. I'm simply more surprised to learn that you don't understand your own feelings on such matters as well as you claim." Deciding that awkwardness around Marcus would be preferable to continuing this conversation, Joan walks past Sherlock again. He follows, a step behind her, adding thoughtfully, "Which is not to say I disapprove. The idea had simply never occurred to me before."
Joan stops in the middle of the foyer, turning a look on Sherlock. "Can we not talk about this?"
"If you insist, but I think it's a topic worth investigating further." His frown stretching and growing more exaggerated, he hums thoughtfully. "Yes, I think Detective Bell would make an excellent partner for you."
"Think about it! He's a man approximately your age in excellent physical condition, objectively attractive, he understands your partnership with me far better than most, which would remove any number of obstacles to your relationship, and there's clearly a..." Sherlock gestures at her vaguely, searching for the right words. "...compatible sexual chemistry between you."
The front door opens. "Hey," Marcus says. Joan stares at a point over his shoulder, her cheeks hot. "Gregson is sending a squad car to pick us up. Should be here in fifteen."
"Thanks," Joan manages.
Marcus nods, moves to go back outside. "Oh, and W - Joan?" He smiles, nearly a smirk. "While I'm flattered your partner think so highly of me, you might want to keep your voices down if you don't want to involve me in this conversation just yet." He shuts the door before Joan can think of anything to say.
"Yes," Sherlock decides a moment later, "eminently suitable."