He was always in a rush, the lonely god. He practically pushed the three of them out of the TARDIS, onto the wet sand of Bad Wolf Bay.
"Rose," he said quickly. "He's half-human, which means he'll age, which means he can be with you in a way I never can. I'd explain more, but the walls between the universes are closing-"
"Doctor!" Donna called from inside the TARDIS. The Doctor spared her a glance, his eyes widened, and he rushed to the console and manipulated buttons and switches and what looked a lot like a bicycle pump before returning to the door.
"Right, where was I? Oh yes-" He took a deep breath. "I love you. And so does he."
The lamp on top of the TARDIS started to glow.
"Mr. and Mrs. Smith, I hope you're very happy together."
The happy couple weren't exactly listening, and the Doctor smiled a sad and wistful smile.
"Goodbye, Rose, me, Jackie."
"Bye! From all of us."
"Oh, yes. Bye."
"Goodbye, Doctor," said Rose, looking into the eyes of her Doctor-
The Doctor ducked inside, there was a noise like rusty cable, and the TARDIS disappeared.
And Rose broke from the Doctor to make a call.
"Hello? Yeah? I'm back. No, Mickey stayed. Yeah-" she smiled at the Doctor. "I've got him."
Jackie Tyler sidled up to the Doctor. "So, you have one heart now?"
"Yeah."
"What else do you have one of?"
The Doctor smiled at her.
"-no, there's a duffel bag at the bottom." Rose said into the phone. "Yeah, I know it's heavy. Book a hotel room under the name 'John Smith'-"
"So, what are you going to do now?"
The Doctor's face creased in that squinty way of his. "Dunno." Inhale. "I'll have to get a real job now."
"What, you've never needed to earn money before?"
The Doctor looked away from her. "Well..."
"-and I'll need you to buy a candle-make it two-a book of matches, some cotton wool, and some rubbing alcohol. And a glass cup. Put them in the bag-without looking-and leave it in the hotel room-"
"You'll have to get a proper name now," Jackie noted. "Can't just be 'John Smith'."
The Doctor considered.
"Always liked 'David'," he said.
Meanwhile, in the TARDIS:
"-I'm sorry," said the doctor as he cupped Donna's face in his hands. "I'm so, so sorry." He took a deep breath. "But I'm not sure how to fix this."
Donna stopped protesting. "You're not going to wipe my memory and leave me on my mother's doorstep?"
"No, of course not! Why would I do that?"
"I don't know, I just thought-" She shrugged. "I don't know. Then what are you going to do? I can't keep being like this, or my head'll explode!"
"Can't wipe your memory, don't be silly. Then I'd have to find some way to keep you from thinking about me for the rest of your life. You wouldn't be able to look at so much as an albino ice phoenix."
Donna smiled at the memory. "We don't have albino ice phoenixes on Earth."
"You know what I mean."
Donna frowned. Useless. All men were useless in a crisis. Who worked as a temp? Her. Who saved the Doctor? Her. Who saved the univ-
Wait.
Saved.
She smiled. "Brilliant."
"What? What are you doing?" the Doctor asked as Donna rushed around the console, pulling levers and pressing buttons.
"The Chameleon Arch! If I can recalibrate it, I can use it to strip the Time Lord part out of me like-"
"-like a wrapper off a lolly! Brilliant!"
"That's what I said!"
It didn't hurt that much, really. Donna later supposed it would've hurt more if she had been converted to a proper Time Lady, instead of whatever she had become. Time Duchess? Time Earl? Time Bastard? Time Bi-
"Done!" said the Doctor. "How are you?"
"Fine." Her mouth was dry. "I need a glass of water, though."
The Doctor instantly handed her an Orangina and straightened up.
"You can fly across the universe, travel through time, and the only drink you have is orange soda?"
"Citrus, actually. And you're fine," the Doctor grinned, and helped her up. "You may notice some memory loss. Incidental things, you know-"
"I can't remember how many Bacon links there are between Hugo Weaving and Bill Cosby-"
"Two." The Doctor plucked the fob watch off of the Chameleon Arch; this one was gold. "Now, what do we do with this?"
It took forever and no time at all.
The Family of Blood was collected up and returned to 1913. Their bonds released, they looked at each other, then at the blue box that had bought them there. As one, they took a step towards it. A red-haired, rather well-endowed woman appeared in the doorway.
"Oi!" she said. "Lunch!" And she threw them a gold pocketwatch. Father of Mine caught it as the TARDIS disappeared.
The Family looked at each other.
Then they opened the watch.
"Well, that's sorted," said Donna. Now, where are we going?"
"I was thinking Barcel-"
There was a noise like rusty cable. Both blinked.
"What?" the Doctor said. "What?"
"That sounds like the TARDIS."
"I know," The Doctor, doing that thing he did with his hair when he was trying to work something out. "But that's impossible..."
A light flashed in the corner of the room, and both the Doctor and Donna turned toward it. It was a lamp, on top of a slowly materializing blue box.
"That looks like the TARDIS." Donna noted. "That looks exactly like this TARDIS, which we are currently standing in-"
"That's impossible! It can't be."
"Doctor, what's going on?"
The door of the blue box opened, and a dark-haired man in a leather jacket stepped out, closer to Donna's age than the Doctor's. He glanced at the heart of the TARDIS, nodded, muttered something that sounded like "bombastic", and walked towards the pair. He bypassed the confused Doctor entirely, stretched his hand toward Donna, and smiled a brilliant smile.
"Nice to meet you," he said, with a Northern accent. "I'm the Doctor."
(Roll credits.)