Martha isn't staying.
She stands with Jack as the watch the Master's remains turn to ash. Even at the distance they're keeping from him, the Doctor's pain is like an elemental force, and Martha wraps her arms around herself, suddenly cold despite the lingering warmth in the air. The light of the fire is harsh against her eyes and she has to turn away.
She attended a lot of funerals over the past year. Small, hurried ones, usually, but there was always a ritual to them. She had to grow numb to them, eventually, with at least the cold comfort of remembering that if she succeeded, none of this would be permanent. The Master's death is different, and though Martha feels for the Doctor and understands this is a huge loss for him, she can't pretend that she's sorry.
She leans against Jack, grateful for his solid presence, and she doesn't look at him as she says, "I'm leaving."
"So am I," he says, wrapping an arm around her shoulder.
"Even if I didn't --" She takes a shuddering breath, emotion raw in her throat. "Even if I didn't love him, I don't think I could stay."
"He's a tough man to love at the best of times," Jack says. "And you deserve so much better, Martha, I promise you."
"So do you," she says, because he died just to see the Doctor again, and it wasn't enough. He's hurting just the way she is.
Jack laughs. "And I have it, too. I was just too much of an idiot to see it, before. But now I know, and I can go home." His voices catches slightly on the word 'home', and Martha leans in closer to him.
"Home," Martha repeats, and the word sounds wistful in her voice, too. "That sounds wonderful."
"What are you going to say to him, when you go?"
Martha frowns, because she doesn't have a good answer for that. Even before she walked the earth she'd had a dozen speeches prepared in her head, for all the things she'd like to tell the Doctor. They've been angry, and desperate, and emotionally overwrought in turn, and none of them have been right.
"I just wish I could make him understand," she says eventually. "I can't imagine how he's feeling, but he isn't alone the way he thinks he is. Maybe we're poor substitutes, all things considered, but neither of us are leaving him forever, are we?"
Jack laughs sadly. "I don't think I'd even know how."
Martha watches the Doctor, silhouetted darkly against the distant flames. "It's not just him, either, it's the whole package - time and space and the TARDIS and all the amazing things you see. But I can't run away with him again, not after everything that's happened. Every time I close my eyes, I think I'm going to wake up in a bunker listening to the Toclafane whirr overhead."
She breaks off then, because she's tired of falling to pieces over this. In many ways, it's a lot harder now it's over. She has no mission, no single-minded purpose to drive all other feelings and doubts from her mind. The world around her is safe and beautiful once again, but not for her. It's all too easy to see wastelands instead of parks and soldiers instead of children.
She doesn't notice she's crying until Jack brushes his thumb across her cheek.
"Hey," he says, softly. "Listen. I've seen more wars than you can shake a stick at, but never anything like this. You have to stop looking after everyone else for a while - especially him."
"That's right. And I'll pull strings to get you some people who are used to dealing with this kind of trauma - you're going to need something a little beyond the NHS."
Martha takes a breath. She feels a mix of anxiety and relief at the offer of help -- it's going to take a while for her to be able to accept help again without believing she's putting others' lives at risk.
It's going to take a while for her to be able to do a lot of things.
The Doctor starts to move back towards them, then, his shoulders hunched and his face blank. When he reaches them, he touches both their shoulders and nods at them in a silent thanks. He walks past them and into the TARDIS.
Martha stops Jack before he follows.
"I wish I could make him understand," she says, looking inside the TARDIS and feeling unbearably sad. "However awful this is, he isn't alone. He's got us. You've known him so much longer than I have -- do you think you can bear to stay with him, tonight? I don't think I can, but someone should."
Jack doesn't look at her for a moment, choosing instead to search the black sky above for his answer.
"I know it's a lot to ask," she says. "But will you do it for me?"
He looks down again and nods. "Anything for you. Probably something I need to do, anyway."
She squeezes his arm. "Thank you."
She leads the way back into the TARDIS. The Doctor is standing behind the console, hands in his pockets and his eyes fixed on some indeterminate point.
"Home, Martha?" he asks, not looking up.
It's the only thing she can imagine wanting. "Please."
The Doctor nods and starts twisting dials.
She walks past him, not quite looking at him, and walks through the corridors of the TARDIS for the first time in a year. She takes the third door on the left and is hit by a wave of painful nostalgia to find her room exactly as she'd left it before they landed in Cardiff, all that time ago. She picks up her red jacket from where she left it on the bed and clutches it tightly.
She gathers up the few belongings that seem important - a change of clothes, much-missed luxuries like toothpaste and her hairbrush. She feels the TARDIS land and has a sudden rush of thoughts like home and safe. She smiles for the first time all day.
Jack and the Doctor are standing apart from each other with a charged kind of silence between them that Martha doesn't understand. Perhaps she doesn't want to. She hugs them both, not letting the Doctor's mechanical response dissuade her, and tells them she'll be back in the morning. To say goodbye, she doesn't add, though Jack knows that and the Doctor has probably guessed.
It's quiet when she steps out onto the street where her mum lives. The air is still warm from a long summer day, a couple of teenagers are drinking beer on a bench at the end of the road, and it's beautifully normal. Tish is already at the door, and so Martha runs to meet her.
She's instantly wrapped up in a flood of hugs from her family, even little Keisha. Her mum presses tea and sandwiches on her, her dad fetches sheets to make up the sofa bed, and Tish curls up beside her on the sofa while they talk and talk. It's obvious all the ways in which they're still hurting, but that might just be something she can do something about, and in doing so, help herself. Slowly, Martha feels a weight lift as she starts to let go of the worries still weighing on her mind -- the Doctor, Jack, the fate of the universe -- and lets herself become immersed in the warmth of her family.