On Martha's third day at Torchwood, Gwen sits on her desk and says, "My boyfriend's away tonight. Do you fancy a girls' night in?"
Martha leans back in her chair, smiles, and says, "Sure. I'll bring the wine."
"Tosh?" Gwen says.
Tosh looks up from her screens where lines are oscillating, matching and diverging in a pattern that's just out of Martha's reach. Tosh blinks a few times and says, "Sorry, what?"
"Girls' night in, my place, tonight."
Tosh's smile is sudden and vivid. "I'd love to. Do I need to bring anything?"
"I'll bring myself," Owen says. "That should be enough."
Gwen shifts on Martha's desk, looking down, another hint of things that Martha's probably never going to know, and Martha opens her mouth to reply but Jack says, "I think you're missing some vital components, Owen. Unless there's something you're not telling us?"
Owen rolls his shoulders a little and stalks back to his hole. Jack winks at Martha and makes a show of turning his attention to the paperwork in his hand. Martha's fairly certain that means he's still listening in on their conversation, so she says, "DVDs, painting our toenails or sex talk?"
"All three," Gwen says, with a delighted grin and slides off Martha's desk.
Tosh glances briefly at Martha and smiles, then her attention's back on her work.
Gwen's coffee table is covered with the remains of Chinese takeaway and there are two empty wine bottles among the mess. Another bottle's on its side next to where Martha's sitting on the floor, legs stretched in front of her. She wiggles her toes and grins at the multicoloured nail varnish on them.
She glances up and Tosh and Gwen are sharing a look. "What?" Martha says, and Tosh slips off the sofa to sit on the floor next to her.
"Tell us about Jack."
Martha laughs and lets her head fall back to rest against Gwen's sofa. "I don't know him enough to tell stories."
"Oh, come on," Tosh says. "You showed up at the door and he let you straight in. Next thing, you're sitting at Suzy's desk."
"And having secret talks in his office," Gwen adds.
"And there's something you both know," Tosh continues.
"It's not-" There's no real way she can explain it. Except, this is Torchwood. If there's anybody she can explain it to, it's these people. "There was a temporal anomaly. We spent a year saving the world together. Well, not together. I was on Earth and he was on a kind of spaceship thing. So we never really talked or anything except for a couple of days before and after." She shrugs. "Still. Saved the world together."
And, because it's Torchwood, Gwen and Tosh just say, "Oh!" as though that explains everything. "So you aren't sleeping with him?" Tosh says.
"God, no!" Martha says, with a little too much vehemence, because she'd definitely had thoughts in that direction, the first time he'd given her that look. But he gave that look as naturally as he breathed and she'd had enough of that.
Tosh's smile is a little shy, a little hopeful, a little something, and it isn't a shock when Martha realises why.
The only thing that surprises her is that it isn't a shock.
"You tell me stories," Martha says. "About everybody. I mean - Jack and Ianto? What's going on there?"
"Oh, who knows!" Gwen says and flops back on the sofa. She swings her legs up to rest where Tosh had been sitting. "They've kissed. They've definitely kissed."
"In front of us all," Tosh adds.
"But then Ianto's all, sir this and sir that."
"They might just have really kinky sex," Martha says, and Gwen giggles. It reminds Martha of how much she's missed, having no friends other than the Doctor.
"Jack and me were trapped in 1941 once," Tosh says, "and Jack seemed pretty in love with a man he met there."
"And there was a woman he used to know, as well," Gwen says. "He was still in love with her."
"Not forgetting the Doctor," Martha says, and then wishes she hadn't. "He falls in love a lot," she adds, before they can say anything.
"I don't think he falls in love," Tosh says. "I think he just... loves."
"I'd prefer somebody who just fell in love with me," Martha says, and she can feel Tosh watching her. She leans over to pour herself another glass of wine and, when she sits back, she's a little closer to Tosh.
Tosh shifts towards Martha, and she doesn't use an excuse. Martha smiles. "I think Ianto might feel the same," Tosh says. She tells Martha about Lisa, and Martha's left feeling sorry for Ianto and sure he wouldn't thank her for it.
"What about Owen?" she asks, and the atmosphere changes. "Did I say something wrong?"
"Owen," Gwen says, "is still hung up on a woman who fell through a time rift from the 1950s."
Martha looks at Tosh but Tosh is staring at her knees, and Martha wishes she'd never said anything.
Eventually, Tosh says, "I think Gwen's the only person in Torchwood with a normal lovelife."
"Depends on how you define normal," Gwen says.
"Well, Rhys isn't a time-traveller, is he?" Martha says. "That puts you a step up on most of us."
"Yeah," Gwen says, and her voice is warm. Martha's pretty sure she's still missing something but she's also pretty sure she doesn't want to know what it is. Especially because her hand is resting on top of Tosh's and she's stroking Tosh's palm with her thumb.
It's easy. Comfortable and simple and easy, even though she thinks it should maybe be frightening. When Gwen goes to bed, staggering a little from the wine, Tosh's head is resting on Martha's shoulder and they're holding hands and it's just natural to turn her head and press her lips to Tosh's.
And Tosh smiles as she kisses, strokes Martha's cheek, and when the kiss ends, Tosh says, "I need to check. You aren't a sociopathic alien who's just using me to get home?"
"No," Martha says. "Completely human."
"Good," Tosh says, and they kiss again.