Author's Notes:
This was written for the Doctor Who Missed Connections Exchange for @thoschei-rights's prompt, which asked for a reunion between a companion and a different regeneration of the Doctor.

Title is taken from the song "Hey Kind Friend" by the Indigo Girls.

Martha lets out a soft exhale after she finally picks the lock on the back entrance to the factory, wishing, not for the first time, that she had a sonic screwdriver. It would certainly make breaking and entering easier.

Once inside, she pulls out the scanner Mickey had rigged up to track the strange energy readings they'd picked up that morning, and follows it down a hallway, keeping her footsteps light.

Martha turns a corner and comes face to face with a woman who looks distinctly out of place. She's wearing a T-shirt with rainbow striping across the chest and blue cropped trousers held up by yellow suspenders, with a grey coat on top, and her blonde bobbed hair doesn’t cover the jewelry glinting on her left ear. At least her shoes are sensible, Martha thinks, glancing down; she’s wearing sturdy-looking boots. “What are you doing here?” Martha asks, immediately wary.

"Martha!" the woman exclaims, face breaking into a broad smile. "Martha Jones!"

"How do you know who I am?" Martha asks sharply.

"Right, yes, of course," the strange woman replies, lightly banging the heel of her hand against her forehead. "Sorry, sometimes I forget I look different. I'm the Doctor."

Martha knows about regeneration, having worked for UNIT – and even if she hadn't, Mickey filled her in on that particular trick of the Doctor. But that doesn't mean this person is telling the truth. "Prove it," she insists.

"We met at Royal Hope Hospital, and when you examined me you realized I had two hearts. We were taken to the moon by a platoon of Judoon," she continues, and Martha smiles despite herself at the rhyme. "Afterwards, I showed you the TARDIS, and asked if you wanted to come with me."

Martha steps towards the woman, and carefully reaches out to take her wrist. She doesn't have a stethoscope with her this time, but she doesn't need one; she can feel that strange double heartbeat pulsing under her fingers.

"Doctor," she breathes. The Doctor grins wildly, and Martha is irresistibly reminded of a different face, with sideburns and spiky hair.

Then a scream echoes down the hallway, shattering the moment.

“Come on!” the Doctor says, and they’re off.

They find a woman, looking startled but thankfully unharmed. "What happened?" Martha asks.

"Who are you?" the woman asks instead, looking between Martha and the Doctor.

The Doctor digs around in her coat pocket before pulling out a familiar slim wallet. "I'm the Doctor, and this is Martha Jones. We're with Health and Safety," she says, quickly flashing the psychic paper at the woman. "What's your name?"

"Gloria," she answers, but she still looks wary. "Strange time for an inspection, isn't it?"

"Clearly one was needed, since something made you scream," Martha says. "What was it?"

"There was someone in my office," Gloria says. "I'd just gone to pull some old records, and when I got back I found him here, doing something with my computer. His back was to me so I didn't get a good look at him at first, but no one else is supposed to be here this late, and certainly not accessing my computer. I was about to leave and call the police when he turned and saw me. He didn't hurt me or say anything at all, he just ran out. Went that way," she says, pointing down the hallway.

"And there's something else," she adds, more hesitantly. "I know it sounds daft but don't laugh, okay? I only saw his face for a few seconds, but he didn't look human."

"That doesn't sound daft at all," Martha assures. "Can you tell us more about what he looked like?"

"He's shaped like a human, more or less – I didn't notice anything odd when I saw him from behind. But his skin was a sort of purple color, and his face was all different. His eyes were much more wide-set than ours, and larger too, and his nose and mouth protruded out," she says, gesturing with her hand.

The Doctor nods along, though whether that means she recognizes the species Martha has no idea. "Mind if we take a look at your computer?" the Doctor asks, already stepping towards it. "Just to see what our trespassing friend was looking at."

"Oh – all right," Gloria agrees uncertainly.

The Doctor pulls out what can only be the sonic screwdriver, even though it's not as thin as the one Martha remembers, and glows yellow rather than blue. She runs it over the screen and files pop up – some text, too much for Martha to read, but some diagrams of what looks like circuitry.

"You guys make computer parts, right?" Martha asks Gloria, "in another section of this building?"

Gloria nods. "Manufacturing's that way," she says, nodding her head in the same direction the alien had gone.

"Think maybe that's what he's after?" Martha asks the Doctor.

"Certainly seems likely," she agrees. "How exactly do we get to where you make these parts?" she directs at Gloria, straightening up.

"Go down the hallway until you reach the stairwell and go down a flight, then turn left and keep going until you reach the big double doors," Gloria answers. "You're not going after him, are you?" she asks.

"'Course we are," the Doctor responds cheerfully. "Don't worry, we'll be fine. You just head home, we'll take it from here."

She heads out of the office, Martha close on her heels, before Gloria can ask any difficult questions like, "since when do aliens fall under Health and Safety's jurisdiction, anyway?"

“I noticed you’re carrying a gun,” the Doctor says, once they're out of earshot.

Martha follows her gaze, looking down at the sidearm holstered at her hip. “Gwen insists,” she says. “I get a lot more use out of my medical equipment, I promise.”

“Gwen? Gwen Cooper?” the Doctor asks, her head jerking up in surprise.

“The one and only,” Martha agrees. “Should’ve known you’d remember her from that intergalactic Zoom call – goodness, that was more than ten years ago now. Though I suppose it’s been longer for you?” she asks.

“Quite a bit,” the Doctor answers. “Well, I suppose that answers what you’re doing sneaking around a factory in Cardiff at night.”

“Had to find some way to occupy my time after UNIT got strangled to death in Brexit-related red tape,” Martha says, not without some bitterness. “I thought about going back to hospital work, maybe setting up my own practice, but Gwen gave me a call. Torchwood may be gone, but Cardiff’s still on a rift. Someone’s got to watch out for aliens coming through it.”

“Must be a lot of work for just you and Gwen,” the Doctor observes as they enter the stairwell.

“Oh, it’s not just the two of us,” Martha says, smiling. “We’ve got Mickey, of course, and sometimes Rhys – Gwen’s husband – comes along. And Lois is our government liaison.”

“Where is Mickey Smith, then? Or is it Mickey Jones, now?” she asks, with a pointed look at Martha’s wedding band.

“Smith,” Martha says, rolling her eyes, though the effect is softened by her smile. “And I’m still Dr. Jones, before you can ask. Mickey’s got the kids tonight.”

“Kids?” the Doctor repeats. “As in plural?”

Martha laughs. “Only one of them, August, is ours. Anwen belongs to Gwen and Rhys, but they're doing some investigating up near Brecon Beacons, so we're watching her. Her and August are thick as thieves anyway.

“But enough about me, what about you?" Martha asks, nudging the Doctor with her shoulder. "You travelling with anyone these days?"

“Oh, yeah!” the Doctor responds, and her whole face lights up. “Three of them, actually – Yaz, Ryan, and Graham. They’re wonderful, Martha, you’d like them.”

“I’m sure I would,” Martha agrees. Between Mickey, Donna, and Jack – and Rose and Sarah Jane, more briefly – she’s got a good track record when it comes to the Doctor’s other companions. “Tell me about them?” she asks.

"Yaz is a police officer – smart, very brave. Ryan's her friend, he's good with people. Graham is his grandad. He was a bus driver, very easy-going."

"Grandad, huh? This body must be better with family members than the one I knew," Martha teases.

"How's your family?" the Doctor asks, and Martha doesn't need her to say anything else to know that she still feels guilty about what happened during the Year That Never Was.

"They're good, Doctor," Martha answers. "Really, they are. Mickey gets along well with them, and Mum and Dad adore August, of course.”

Martha wants to say more, find the right words to convince the Doctor that she and her family aren’t irreparably scarred from the Doctor's impact on their lives, but they're reached the double doors leading to the manufacturing area. The Doctor pushes the doors open without needing the sonic. Either they're supposed to be unlocked – unlikely, Martha thinks, at this time of night – or the alien has already passed through here.

They step through the doors, both going silent in unspoken agreement. They walk further into the dim room, Martha's ears straining against the quiet for any noise – and then she hears it, a soft clacking sound in the distance.

She can tell the Doctor hears it too, because she stops and turns her head in the direction of the sound, exchanging a quick glance with Martha before walking towards it.

They draw closer until finally they're in sight of the alien, who is kneeling on the ground, pulling objects – some sort of electronic equipment, Martha thinks, but she can't tell more in the gloom – from the shelves next to him and placing them in a bag.

The Doctor steps into his sightline. "Hello there!" she says, giving a little wave. "Mind telling me what you're doing here?"

The alien startles, lurching to his feet and backing against the shelf. Even with the dark and his unfamiliar features, Martha is fairly certain he looks terrified.

"Easy," Martha says, stepping out to join the Doctor. "We're not going to hurt you."

His posture relaxes slightly at this, but he doesn't move away from the shelf, or answer the Doctor's questions.

"I'm Martha," she tries, "and this is the Doctor. What's your name?"

"I am Zardi," he answers.

"Nice to meet you, Zardi. How come you're on Earth?"

"I was travelling when my ship encountered – I don't know what it was. Some kind of tear in space? It deposited me above this city. I managed to land by the bay, but several of my ship's systems were damaged. I need these parts to repair them."

His eyes shift over to the Doctor. "I'm sorry for stealing, but I have no local currency. And I'm sorry for frightening that woman; I thought the building would be empty by now."

"Quite understandable," the Doctor says. "Now, how about we help you patch your ship up?"

"You'll help me? Really?"

"Of course we will! What parts do you need?" the Doctor asks, wandering over to the shelves and picking up a bit of equipment, making a face at it.

"And – and you're sure it's all right? To take some of this?" Zardi asks uncertainly.

"Don't worry about it," Martha assures. "I'll make sure the company is compensated for whatever we end up taking." Torchwood may no longer exist, officially, but Lois manages to keep a good chunk of their funding coming.

With Martha and the Doctor helping, it doesn't take long to collect everything Zardi needs, and he gratefully accepts the Doctor's offer of help with his repairs. They leave the building and head towards his ship.

"So," the Doctor says as they follow Zardi to the bay shore, "aren't you going to say anything about the new look?"

"It's less strange than that time you grew a new person from your hand, honestly," Martha says. "Besides," she adds, looking at the Doctor slyly, "it's not that different. I bet you still look great in a tux."

"I still attract trouble in one, too," the Doctor says, sounding just this side of petulant.

Martha snorts. "Like you don't attract trouble no matter what you're wearing – or how you look, for that matter."

They reach Zardi's ship, which has been concealed under a dock, and go inside it. Zardi goes to the front to work on the cockpit controls, leaving the Doctor and Martha responsible for the engines.

Martha quickly realizes that the technology is far beyond her, and the most help she can offer is handing the Doctor tools and parts when asked.

"Too bad Mickey's not here," she tells the Doctor. "Mechanics were always much more his thing than mine."

"I'm not sure any human mechanic would be much help with these engines," the Doctor says. "Besides, he'd complain more about having to hand me stuff," she adds, flashing Martha a grin.

"Probably," Martha agrees.

They work in companionable silence for a while, until Martha can no longer hold back the question that's been nagging at her this whole time.

“Doctor," she starts, not without some amount of trepidation, "what happened to Rose and Donna?"

“Oh, they’re fine,” the Doctor says lightly, but Martha knows better than to take it at face value. “Rose is back in that parallel universe, along with her mum and the metacrisis Doctor. And Donna went back to her family. She’s married now, too.”

“I didn’t think she’d ever want to stop travelling with you,” Martha says, thinking about what Donna had told her after Messaline. I'm going to travel with that man forever.

Guilt flickers on the Doctor’s face, and Martha realizes there’s something she hasn’t been told. “Doctor?” she presses. “What happened?”

“The metacrisis. It gave Donna all the knowledge of a Time Lord, but it was too much for a human brain. I had to remove that knowledge to save her – but the only way to do that was to erase all her memories of me. She doesn’t remember she ever travelled with me.”

How awful for Donna to have that taken away from her, Martha thinks. And how awful for the Doctor to have had to do it to her.

"I'm sorry," Martha murmurs, at a loss for anything else to say. She covers the Doctor's hand with her own, gives it a light squeeze.

“It happened a long time ago for me, Martha,” the Doctor says, and Martha wonders if that actually makes it any easier. “I saw her afterwards, from a distance and she’s still Donna,” the Doctor adds. “She doesn’t need me to make her brilliant. None of you do.”

Martha recognizes the compliment for what it is, and she doesn’t disagree, exactly – but she wonders how much the Doctor has to believe that, to live with the memories of people left behind.

"That ought to do it!" The Doctor says, clicking the engine cover back into place and snapping Martha out of her thoughts. "Let's see how Zardi's getting along.”

Zardi, it turns out, has made quick work of the rest of the damage and has declared his ship spaceworthy once again.

"Will you be able to get home?" the Doctor asks. "I don't know how far off course the Rift pulled you."

"I have already checked the navigational system," Zardi says, smiling excitedly. "The – what did you call it? The Rift? – actually took several days off my journey."

"In that case, we'll let you get on your way."

"Thank you for all your help, Martha and Doctor."

Martha and the Doctor leave the ship and walk a safe distance down the shore. After a few minutes, the ship takes off and swoops gracefully into the starry night.

“Well, there’s that taken care of,” the Doctor comments. “I suppose it’s time for you to be getting home, then – unless you want to meet Yaz, Ryan, and Graham?” she asks hopefully.

“Of course I want to meet them!”

The Doctor grins, looking pleased. “They ought to be heading back to the TARDIS by now; it’s only a few blocks from here.”

“How’d you meet them, anyway?” Martha asks as they walk.

“I fell on a train they were riding – literally fell, crashed through the roof and everything – and stopped a nasty piece of bioweaponry from electrocuting them,” the Doctor answers. “What?” she asks, when Martha can’t hold back a small smirk.

“Nothing!” Martha says hurriedly. “It’s just – you don’t do things by half, do you? So, what happened next? No, wait, don’t tell me – they helped you foil a dastardly alien invasion, and as a reward you asked if they wanted to come with you?” Martha guesses.

“You’re only half right. They did help me stop a Stenza warrior, but I didn’t invite them along. I’d become separated from the TARDIS, actually. I built a teleport to get me back to her, but it brought the others along too by accident.”

They turn a corner and three figures standing next to a very familiar blue box come into view. “Ah, there’s the fam!” the Doctor says as they approach. “Fam, meet Dr. Martha Jones, an old friend of mine. Martha, meet Yaz, Ryan, and Graham.”

Fam, Martha wonders. That one little word is a bigger departure from the Doctor she knew than the new gender, face, and outfit put together.

"Another doctor, huh?" Ryan asks.

"I'm a proper medical doctor, unlike her," Martha says. The Doctor pretends to look affronted.

“So while we were chasing energy signatures all over Cardiff, you two were busy socializing?” Graham asks.

“Oi! Martha and I were quite productive, thank you!” the Doctor responds, and Martha can’t help but smile to herself at the teasing. “We found the alien and sent him on his way. He was a nice chap, actually.”

“How do you know the Doctor, anyway?” Yaz asks Martha.

“I used to travel with her,” Martha answers, tripping over the pronoun for just a moment. Thinking of the Doctor as a woman now hasn’t been hard, but applying it backwards to the Doctor she knew is stranger.

“Really?” says Yaz, looking interested. “You must have some stories to tell, then.”

“Quite a few,” Martha says. “Carrionites at Shakespeare’s Globe, a sentient sun, Daleks in 1930s Manhattan – have you lot met the Daleks?” she asks.

“Once,” Ryan answers, looking grim. "Wouldn't want to come across another."

"No," Martha agrees. "Fortunately, they don't crop up too often."

“Why’d you stop travelling?” Yaz asks.

Martha glances at the Doctor on instinct. “I missed my family,” she says. “And I couldn’t put off my medical exams forever, anyway,” she adds lightly. It's an easier explanation than my family was held hostage by a psychopathic Time Lord for a year because of me, or it was the only way I was going to stop fancying the Doctor like mad.

But perhaps a bit of the tension bleeds through anyway, because Graham clears his throat and says, "We'll wait for you in the TARDIS, Doc," unsubtly gesturing for Ryan and Yaz to go with him. Yaz shoots the two of them one last look before she follows them in.

As the door clicks shut in front of her, Martha suddenly misses that life so much her chest aches. She misses seeing the incredible and doing the impossible on a near-daily basis. She misses being that close with the Doctor, even if it wasn't in quite the way she wanted. She misses being young and carefree enough to just take off into the unknown.

But only for a moment. She loves the life she has here, the career she's worked for, the relationships she's built. She still gets to see and do things most people could only dream about – but now she gets to go home afterwards, to the stability of a family.

“You could come with us, you know,” the Doctor offers in a deceptively casual tone, and Martha wonders if some wistfulness had shown in her expression. “One last trip, for old times’ sake?”

“It’s tempting,” Martha admits, running her hand lightly along the TARDIS’s door frame. “But no. I’ve got a kid now; I can’t just go gallivanting through space and time anymore. And don’t say you could have me back a minute later – Mickey told me about that time you returned Rose a year after you meant to.

“You’ve got them now, Doctor,” Martha continues, quieter, tilting her head towards the TARDIS doors, where Yaz, Ryan, and Graham wait on the other side. “You don’t need me to tag along.”

The Doctor’s expression goes soft, and the next thing Martha knows she’s being wrapped in a tight hug.

“Oh, Martha Jones. It was good to see you again,” the Doctor says, close to her ear.

“It was good to see you too, Doctor,” Martha says, and presses a quick kiss to the Doctor's cheek before pulling away. She wants to tell the Doctor to drop by on purpose sometime, or ask if she's still got Martha's mobile, ready to come if needed. But she knows the Doctor doesn't casually check up on people, doesn't like to look back any more than she has too. “You look after yourself, all right?” Martha says instead.

The Doctor gives her a nod, which Martha supposes is about as much of a promise as she can expect, given the amount of trouble the Doctor tends to find. The Doctor steps inside the TARDIS, pulling the door closed behind her.

Martha watches as the TARDIS dematerializes, with the same old groaning noise it always made, and she wishes, just for a moment, that she had gone with them. But that vanishes along with the TARDIS, and Martha smiles to herself as she turns to go home. She can’t wait to tell Mickey about what happened.