When Ruby hugs the Doctor as they leave 1813, the Doctor has to swallow hard around the lump that forms in his throat.
Ruby disappears to her room for some well-needed sleep, but the Doctor sits by the console, listening to the hum of the Tardis as she spins idly. He looks at the ring on his pinky, and traces its design gently with his index finger. He thinks about all of the millions of millions of millions of dimensions Rogue could be in, and how impossible it is to ever find him. The lump relodges itself in his throat.
Gently, the Doctor removes the ring; he sets it on a small scanner on the Tardis console. A few seconds later, "DNA scan completed" scrolls along a nearby screen in Gallifreyan. The Doctor pushes another few buttons and pulls a few levers. Within a few minutes, the Tardis is configured to run a constant background sweep for a dimension that contains Rogue's DNA.
It could take the Tardis an eternity to find the right dimension - perhaps longer than even he can live. But if the scan runs long enough, there's a chance that someday, some version of himself could find Rogue. It's what he has to tell himself in order to maintain his sanity when Rogue's last words echo in his head.
When he puts the ring back on, he feels something at the back of his throat, and he coughs.
When Ruby stumbles into the Tardis console room hours later, still softly rumpled from sleep, the Doctor grins at her as though nothing's happened.
"I've got the perfect place for us to go - have you ever heard of the Torani people? Their planet is entirely beaches, isn't that fantastic? And they have the best flower festivals in their entire galaxy, people travel across the stars just to see them once," he says to her. She eyes him, clearly not believing his facade but not awake enough to do anything about it.
"Beaches don't have flowers," she says instead. The Doctor rolls his eyes.
"Alright, so the planet isn't actually entirely beaches, they also have greenhouses where they grow the flowers for the festivals."
She laughs, but she's clearly still unconvinced that he's actually alright.
"I'd love to go," she says, her smile looking only slightly forced. The Doctor pretends not to notice her scrutiny, and pulls a lever, spinning the Tardis toward the festival's biggest ever year.
When they step out the door, he can tell Ruby immediately forgets herself as she looks wonderstruck at the sight in front of them. There are flowers everywhere - petals of every color strewn across the walkways in front of them, cheerful bunches of flowers set on top of almost every surface they can see, and hundreds upon hundreds of flowers strung together and hung overhead. Ruby grabs his hand, and pulls him into the streets, merging with the crowd of laughing, talking people of all different species.
For once, they simply have a lovely day. No one needs saving, there's no alien invasion or threat. They're both laughing at nothing when out of the corner of his eye, the Doctor sees a figure in a blue coat with a mop of brown, curly hair on his head, and his hearts leap into his chest. He turns, a foolish, stupid hope pooling inside him. It's extinguished instantly when he gets a better look at the man - obvious alien features mark the man as clearly not the same as the one he'd lost in 1813. He hates himself a bit for how disappointed he is.
He begins to cough suddenly - a brief but deep, hacking cough. He feels something fly out of his throat into his mouth, and he spits it out into his palm. It's a small purple petal - wisteria, maybe? He doesn't see anything like it when he looks around at the petals fluttering in the air around them, but that doesn't mean much - he probably swallowed it earlier when they were passing through a different section of the festival. The Doctor brushes it off his palm and lets it fall to the ground to merge with the other petals on the walkway. The petal is trampled under his and Ruby's feet, and he forgets about it completely.
Later, after he's dropped Ruby back off in 2024, he feels it again - that lump in the back of his throat. He inhales too sharply, and all of a sudden he's coughing again - the same hacking cough as earlier in the day. Eyes squeezed shut against the pressure, he coughs and coughs as he can feel something expelling itself from his throat. When he opens his eyes, there's a spray of saliva-damp wisteria petals plastered across the Tardis console in front of him.
This can't be happening. Not to him, he'd never believed he was capable of it. It hadn't ever happened to him before - not with River, not with Rose, not with any of the people he'd loved and lost over the hundreds of years he'd been alive. Hell, he isn't even a real Time Lord, it shouldn't be possible for him of all people-
He walks to the doors of the Tardis, opens them up to see the stars of the galaxy she's currently orbiting. He sits down on the doorstep, rests his head in his hands, and lets out a blood-curdling scream at the unfairness of the universe.
When he gets up and walks back to the console, the wisteria petals seem to taunt him until he finds a rag to wipe them away.
He decides not to say anything to Ruby about his affliction. He manages this for about twenty-four hours into their next trip before she realizes something's wrong.
"Doctor, are you….sick?" she asks tentatively after he's cleared his throat for about the fiftieth time that day. She's never seen him so much as sniffle during all the months they've been traveling together - not even when she'd picked up the worst flu of her life from a trip they'd taken a few months back.
"Of course not, I'm fi-" he tries to say, but is cut off by a series of coughs that lasts several minutes. He tries to turn away, tries to hide the pink and purple tinged petals that are erupting from his lungs. It doesn't work.
"Doctor, what the hell." she says, a statement more than a question. "Are you….coughing up flowers?"
He thinks about lying, he thinks about obfuscating and making up some vague excuse, but he can't, not to her.
"It's…something that can happen to Time Lords. It's rare, but sometimes when we meet someone…we connect, on a psychic level. Sometimes we connect so deeply that it creates a psychic bond, without any intention from either person involved." Ruby's frown deepens, and he continues on before she can ask him what he's on about.
"If a connection like that gets formed, and then it's broken - if we're separated in time or space, or the bond isn't accepted by the other person - it causes backlash that can manifest physically. The broken connection literally grows inside you, and it won't stop until the link's re-established. Usually it takes the form of a plant, something that symbolizes the moment that initiated the connection." Ruby takes a closer look at the small petals that are coating his sleeve and the floor of the Tardis, but he can tell she still hasn't made the connection. He sighs.
"There were wisteria vines hanging above the pathway right outside the Pemberton mansion," he says, and understanding dawns in her eyes. She nods.
"I didn't think- I've known of the Hanahaki disease all my life, all Time Lords do, but it's so rare. Many of us went our entire lives without even knowing someone affected by it, it's not like it happens every time we fall in lo-" he cuts himself off, unable to actually speak the word aloud. "It's not like it happens often."
"What causes it?" she asks. "If it doesn't happen every time."
"No one really knows," he says. "Some people think it has something to do with soulmates, some people think it has something to do with brainwaves. Depends whether you ask a poet or a scientist. One man's idea of destiny is another man's idea of an incurable disease." He tries for a wry smile, but it doesn't quite work.
"When you say incurable…what happens if you don't find him again?" she asks.
"The flowers keep growing in my lungs until- until there's no space left for them to grow any more," he says.
"So you're literally dying of a broken heart?" she asks him, as though she can't quite tell whether to laugh or cry.
"That pretty much sums it up, yeah," the Doctor replies, a lightness in his voice that doesn't fool either of them.
"Doctor, I can't decide if that's romantic, or the most horrifying thing I've ever heard," she says.
The Doctor flashes a too-bright grin at her. "Can't it be both?"
"Isn't there anything else we can do? Some kind of- I don't know, space cure, something that'll stop it, or slow it down?" she asks him later, once the initial horror of his situation has faded. The Doctor hesitates before replying, and she sees it on his face. "Doctor, if there's anything, we have to try-"
"There's one way that can cure hanahaki that's in its early stages, but it's- it's not an option," he says, begging her silently to not ask more. She glares at him and he sighs. "Time Lords have a sort of trick we can use, a way to cheat death. When we're dying, we can sometimes heal ourselves by changing our face, becoming someone else. Regeneration energy - that's what the process is called, regeneration - can be used to burn the link out of our minds, taking the flowers with it. But there's a cost. The trauma of burning the link doesn't just break the connection, it also burns all the memories you have of the person."
"You'd forget you ever met him," Ruby says.
"More than that, the scar tissue left where the link was means that if you ever meet them again, if you even try to remember, it can break your mind. There's a risk that it can break both your minds, if the backlash is strong enough. If I broke the link, I could never find Rogue again - it could kill us both."
Tears begin to spring into Ruby's eyes again. "But Doctor, if you'd die anyway-" she starts, and the Doctor grabs her hand and squeezes it.
"I've lived for thousands of years, Ruby Sunday, and I can tell you that some things are worth dying for." She shakes her head, refusing to accept it, and pulls him into another hug, squeezing him tightly. When she finally releases him, there's resolution on her face.
"Well, it's not going to come to that, because we're going to find him," she says. "Where do we start?"
He tells Ruby about the scan he's already set up for Rogue's DNA, and how improbable it is that it'll work in time.
"Isn't there any way to, I don't know, speed it up somehow? The Tardis is a time machine, can't she run the calculations at double speed or something? Or- what if you found a planet, set up a computer running with the calculation, and returned a hundred years later to see the results?" she asks him. The Doctor shakes his head.
"The Tardis can't affect her own timeline - we can't speed up or slow down time as she experiences it. And we can't do the calculation anywhere else - scanning dimensions is Time Lord technology, there's nothing else in the universe that would be able to pull the dimensional energy needed to be able to find him," he says.
"Can we narrow down the number of dimensions somehow? Give her less options to run through?" Ruby asks. The Doctor shakes his head again.
"If the trifold hadn't broken, we could have scanned its residual energy and used the signature to determine a more limited set of possible dimensions, but it's useless as it is," he says. Ruby looks at him desperately.
"What if you'd been able to get an energy reading before it broke? We could go back to the moment and get the reading right when Rogue activates it, we could hide outside the window or something so we didn't interfere or change anything-" the Doctor grabs her hand and squeezes it, cutting her off.
"Ruby, we can't cross our own timeline. You'd have to be right in the room to be close enough to get a reading, and even if we tried to hide or disguise ourselves there's a chance we'd make a mistake and that our past selves would recognize us. We can't risk creating that kind of paradox," he says. She frowns, looking disappointed, but then seems to reconsider something.
"Doctor, you said we can't cross our own timelines, right?" she says. The Doctor nods, not sure what she's getting at. "What if it wasn't us who did it?" The Doctor listens as she explains what she's thinking, and a slow grin spreads across his face.
"Ruby Sunday, you might just be a genius," he says. "I know just where we can find someone for the job."
"Kate Stewart!" the Doctor exclaims, exiting the Tardis into UNIT's headquarters. "Can we borrow one of your soldiers?"
Turns out, there are a lot of UNIT volunteers for a mission to travel back to Regency-era England where the only qualifying criteria are 1) being a stranger to the Doctor and Ruby and 2) being able to use a handheld energy scanner. Once Kate selects someone - a tall middle-aged man with cropped black hair - it's only a matter of outfitting him with the best regency outfit the Tardis has to offer, psychic paper, and a scanner before dropping him off at the Pemberton mansion a week before the Doctor and Ruby's visit. He's under strict orders to make sure he's inside the room right before the Chuldur stage their cosplay wedding, and to - without interfering at all - take an energy reading in the seconds between when the trap is activated and when the trifold burns itself out.
It's a risk, and the Doctor knows it. By dropping the man off a week before their visit and picking him up a week after, there should be enough buffer time to avoid cross-contamination between the time streams for the two different Tardis visits, but they're still technically interfering with their own timeline. Using a stranger means that neither the Doctor nor Ruby would be able to recognize him when he appears in the past, but it also means that the man's behavior is unknown - there's the chance that he'll lose his head and try to interfere with events as they play out. There's also plenty that can go wrong aside from the paradox-causing variety of mistakes - if the man simply isn't able to make it into the room at the right time, or if there's a malfunction with the scanner, that'll be that. This is their one shot - between their first visit, Rogue, the UNIT soldier, the Chuldur, and the energy from the triform itself, they're already interfering quite a bit with the timeline at this point. If it fails, there are no do-overs - the Doctor won't risk introducing more time travelers to the moment.
With bated breath, he and Ruby travel forward in time two weeks from when they dropped the man off. They open the door to see him standing in front of the Tardis, grinning. He pulls the scanner out of his pockets and triumphantly hands it to them.
"That," the man says, "was amazing."
Everything had apparently gone perfectly - he'd been able to lurk in the room all night so he'd been guaranteed to be there when the Chuldur locked the doors, and with everyone in the room transfixed by the Chuldur themselves and Rogue's sacrifice, he had no trouble at all with surreptitiously pulling out the scanner and getting an energy reading at exactly the right moment.
The Doctor and Ruby thank him vigorously before dropping him back off at UNIT, and then the Doctor plugs the scanner into the Tardis console so she can analyze the energy readings off of it. With any luck, it'll narrow down the potential dimensions to a small enough range that the Tardis can parse it in a day or so.
The Tardis beeps, and writing in circular Gallifreyan begins to scroll across one of the console screens. After a few seconds, a number appears on the screen, flashing bright red. The Doctor feels something solidify in his throat, and he starts to cough. He pulls out one of the handkerchiefs he's started carrying around in his pockets, and spits out a small glob of tiny purple and blue petals.
"Doctor-" Ruby says, worried. The Doctor waves her concern away.
"I'm alright," he says, smiling weakly at her.
"What does it say? Is it…did it work?" she asks, trying and failing to keep the quaver out of her voice. The Doctor exhales slowly.
"The energy readings didn't narrow down the possibilities as much as I'd hoped. It's down to about 32 million different universes. The Tardis can scan about one dimension every second - at that rate, it'll take about a year of her running constantly to check every single one of them," he says.
"Is that- is that fast enough?" Can you make it that long? Is the unspoken question behind her words.
"I wish I knew, babes," he says, staring at the balled up handkerchief in his hand. "I really wish I knew."
He assures her, later, that a year is only the worst case scenario - there's a decent chance it will take much less time than that. They could get lucky, after all - Rogue could be in the very first universe the Tardis searches.
But as the Tardis begins to search, he's not in the first universe, or the second, or the sixtieth. The Doctor fiddles with the controls until the console displays in English, and together they sit and watch the number slowly tick up: 60 dimensions searched, 120 dimensions searched, 180 dimensions searched. No results found.
They sit and stare at it until dimension 300, at which point the Doctor brightly announces he's taking Ruby home. There's no point in the two of them just watching the counter, the Tardis will let him know the second it finds a hit, he tells her. He can come find her as soon as anything changes. She tries to argue, but he insists, and eventually she's shooed out of the Tardis and back into the Sunday family flat.
The Doctor turns away from the console and doesn't look back. He wanders into the library and reorganizes a few of the shelves. He rewires a toaster so that it plays Earth eighties pop music when you make regular toast, and nineties rock when you heat up bagels. He adds a setting on his sonic that's able to read the density of certain types of lava rocks only found on Raxacoricofallapatorius.
Eventually, he sleeps, and he dreams of walking through the wisteria corridor from the mansion, but now the pastel petals are dripping a deep red blood. He walks through the corridor in a haze, and sees a body at the end of it, just like he did on that night.
This time the shriveled husk of a body doesn't belong to the Duchess. This time, it's Rouge's corpse that he kneels down besides.
He wakes up choking on clumps of wisteria flowers, and begins to cough, and cough, and cough.
"Do you think Rogue's growing flowers in his lungs too?" Ruby asks him one day when she catches him glancing at the counter (1,209,643 searched; 30,799,459 remaining) while they're standing at the Tardis console after a trip.
The Doctor shakes his head. "It only affects Time Lords, as far as I know. Even if…even if he feels the same way I do, I don't think it would affect him like this." He doesn't say what he's thinking - that trapped in a hostile barren dimension with six Chulder, any type of physical ailment slowing you down can mean the difference between life and death. If Rogue is coughing up flowers, it might very quickly be the end of him, long before the disease has run its full course. The Doctor can't bear that thought, can't bear the idea that he might be the cause of Rogue's death on top of being responsible for his exile. He has to believe that he's the only one suffering from this sickness.
He also doesn't say the other thing he's thinking - that Hanahaki disease can be one-sided. The psychic link only requires one person's affection to form, not two. Sure, Rogue clearly was attracted to him, clearly felt something. But it's a far cry between feeling something and, well, being in love. The Doctor knows all too well how possible it is to kiss and flirt and even sacrifice yourself for someone without being in love. He's done it himself, more times than he can count. For all the Doctor knows, Rogue made a snap decision and regretted it the second after he triggered the trifold. Maybe Rogue hates him for being the reason behind his exile. There are as many possible ways for Rogue to not love him as there are possible dimensions he could be stuck in.
He thinks about what he'll do if they find Rogue, and the flowers in his lungs don't heal, and he finds he doesn't know. His throat begins to fill with petals, and he begins to cough until his throat is raw and he can hardly breathe. He decides it's better to not think about that possibility.
Time passes. The scan keeps running.
"Did you know wisteria flowers are associated with immortality in some Earth cultures?" Ruby asks him one day. "Immortality and romance. You might even say they're a symbol of undying love." The Doctor looks at her, an eyebrow raised at the irony. "No, I know, but maybe it's a sign, Doctor. Maybe it's a sign that you're destined to find him."
The Doctor hasn't believed in destiny in a long, long time, but he doesn't say so. Better to let Ruby have some of the hope she's grasping at than to crush it now.
More time passes, and the disease is getting worse.
The Doctor can feel it with every breath he takes now. It isn't just flowers any more - he can feel roots and vines starting to dig themselves deep into his lungs. He can't say Rogue's name anymore - every time he tries to shape the word, clusters of flowers and stems fill his throat until he chokes on them, triggering a coughing fit so bad that it leaves him winded for long minutes afterwards. So he contents himself with his thoughts, with his memories of that perfect, horrible night when their paths had crossed. He loses himself in thoughts of getting to kiss those perfect lips again, run his hands through Rogue's beautiful curls, dance together again, this time in the privacy of the Tardis with no one there to see...
He's pretty sure he can feel the vines coiling thicker in his throat when he surrenders too deeply to these fantasies, but there are some things he just can't help.
He thinks about the possibility of regeneration.
There are ways he could forget Rogue and still save him. The Tardis does have a limited autopilot - he could program her to send Ruby to pick Rogue up and drop him somewhere habitable without any involvement from the Doctor himself. He could save Rogue and himself.
But he thinks about the utter confidence with which Rogue had said "find me." He thinks about the look in the other man's eyes when he'd seen the Tardis for the first time, his look of stunned wonder when he'd seen all of the Doctor's regenerations and realized who and what the Doctor was.
He thinks long back, to a past version of himself who'd forgotten Clara. He thinks about the void it had left in him, the agonizing well of nothingness that had been so much worse than simply losing her.
He doesn't know what Rogue feels for him, he doesn't know if the other man's feelings have changed at all since they last met, but he does know that he'd rather die trying to figure it out than live having given up on him.
He won't be regenerating to get out of this.
For a while, he still travels with Ruby, taking her to see all the wonders of the universe. It's not the same as it was - he catches her giving him worrying glances as he has to spit out larger and larger clumps of wisteria. Even with the Hanahaki casting a pallor over everything, it's magical to see the galaxies through her eyes, to see her wonder at purple beaches and green skies, at comets and supernovas and more stars than even he could count. To be able to help people when they run across people who need them - which is still more often than not. Even as he knows he's slowly dying, the Doctor feels as alive as he ever did.
But the coughing fits are getting worse.
The small clusters of wisteria flowers begin to turn into longer vines that he has to slowly, painfully pull out of his own throat in order to breathe clearly. His voice starts to sound dry and hoarse all the time, and there are some days where walking for too long starts to make him feel dizzy.
He tries to find slower places, safe places to take Ruby to, but danger still follows him now as surely as it ever did. When one trip leads to the two of them almost getting killed because a coughing fit gives away their hiding place, when Ruby has to risk her life to help him back to the Tardis because he isn't able to run when he needs to, he knows it has to be the last trip. He promised Carla Sunday that Ruby would be safe with him, and he has to face the fact that keeping his promise means they can't travel together anymore.
So he parks the Tardis on the street corner by the Sunday family's flat - Ruby won't hear of him going anywhere else. At first, he stays in the Tardis, but slowly Ruby coaxes him into their guest room. He finds himself being served tea and hot soup by Carla after the worst of his fits, while Ruby carefully sweeps up the flowers that have spilled all over their living room. He spends hours sitting in Cherry Sunday's room, talking and laughing together as only two old invalids can.
The scent of wisteria is ever present. He thinks he might grow to hate it, to hate the soft pastel lavender and pink and blue flowers that are killing him, but he can't manage it. It feels too much like hating Rogue, and he knows that's something he could never do.
Every day, he and Ruby check the Tardis's scanners to see if she's found the right dimension. Every day, it's the same - the number of scanned universes slowly ticks up, but none of them contain Rogue's DNA. They've gone through about half of the 32 million dimensions by now - six months down, six months to go before they make it through all of them. Neither he nor Ruby acknowledge that it's time he might not have.
Neither of them acknowledge it when the wisteria petals he coughs up start to be tinged with blood.
Talking at all has hurt for a while now, but even breathing is starting to become a struggle. What hurts the most, however, is the look of relief in Ruby's eyes every morning when she brings him tea and doesn't find a flower-covered corpse, because he's starting to accept that one day soon she'll walk into the room and find what she fears most. He can hear her sobbing, sometimes, late at night - she thinks she's being quiet enough to keep him from hearing, but she doesn't realize a Time Lord's hearing is a bit better than a human's. She's so young, she deserves better than to watch a friend waste away like this.
Worse than that, he has more to ask of her than just watching him die. Rogue is still out there, and someone needs to pilot the Tardis to find him once the search finally comes to its conclusion. He's already set up a subroutine to take the Tardis to wherever the final result is, then to Rogue's ship, and then back to 2024. All it needs is someone to push the button to activate it once the result is there - the Tardis should take her right to him, so she wouldn't even need to leave the ship.
He tries asking Ruby about it, once. She won't let him continue past the phrase "after I'm gone," and insists that it won't come to that, that the scan will finish in time. He doesn't push, but instead records a message for her in the Tardis, telling her how she can save Rogue, begging her to do this one last thing for him. He knows that sooner or later, she'll make her way to the Tardis, afterwards, and she'll see the message. He knows it'll hurt her, but she'll do it.
Aside from Ruby, he's made his peace with dying by now. He thinks some of his past selves might have fought more, but he's lost so, so many people over the years, and he just doesn't have it left in him to fight for himself anymore. Everything just hurts so much. There's nothing more that can be done at this point anyway - regeneration can cure Hanahaki in its early stages, but by now the damage the flowers have done to his body is too severe - even regeneration energy isn't enough now to both heal him physically and burn out the rest of the bond. There's five months left on the scan, and he knows he won't make it to the end.
One night, he wakes up gagging on a cluster of flowers so large it feels like they're about to tear his throat wide open. He leans over the side of the bed and throws up into the tiny trash can beside the night stand. He looks down at the mess of blood and bile and flowers, and feels himself breathe shallowly around the spirals of vines in his lungs that prevent him from even exhaling fully, and he knows. He knows if he goes back to sleep tonight, he won't be waking up in the morning.
He has to get to the Tardis. She'll take care of his body - he knows he hasn't been able to spare Ruby much, but he can spare her that nightmare at least. Taking shallow, careful breaths, he cautiously leverages himself out of the bed and creeps out of the flat, taking care to avoid the floorboards he's heard squeaking when they're stepped on. Once he's out of the building, the coughs that he's been holding back begin to spill out of him, covering the street in front of him in more petals than can physically fit in his lungs. Time Lord technology, he thinks to himself wryly. Bigger on the inside until the very end.
Each cough brings unbearable pain, and there are tears streaming down his face as he slowly limps to the door of the Tardis and pushes it open. He's fully prepared to collapse on the floor just inside the doors, but when he steps inside he's greeted with a gentle, pulsing green light instead of the white light he was expecting. He looks over to the console in front of him, and he can see the screen that for months has displayed the message "No results found."
Now, it spells out, in triumphant flashing green letters, "Dimension located: DNA match found."
The Doctor gags again, and falls to his knees to throw up more flowers onto the floor of the Tardis. When he pushes himself up off the floor, the pain is infinitesimally more bearable than it was a moment earlier.
He drags himself over to the screen, double checks the results. They confirm what the screen has already said: that the Tardis has found a dimension with a life signature that matches Rogue's DNA.
He picks up the phone on the Tardis console, and dials Ruby's cell phone number.
"Ruby," he whispers, voice long since shredded from the flowers, "Ruby, I found him."