A young girl rapped on the door, a quick, persistent sound. He reopened the door. She grinned, light and easy. Her golden brown hair was plastered to her head and shoulders by the rain. She wiped it away from her deep light brown eyes. "Don't worry about the Doctor. I mean, don't not think about him, and I'm sure he'd like it if you still looked out for him, because you are his friend, and you know he'll always think about Donna, but don't worry." Her grin spread into a warm smile. She seemed to flicker out of view with the TARDIS. "He's never been alone." She was completely transparent now. As she faded, he heard, "He's got me."
He was sad, very sad, and very hurt. Martha, Jack, Mickey, Jackie… Donna. Rose. He closed his eyes against the threatening tears.
"Oh, be that way. Fine. Fine! You're not supposed to know, but, oh, goodness, you know I never liked to see you cry, Big Brother. Really!"
The Doctor's eyes shot open. He shook his head. "No. No, this is impossible…"
"Well, we've always been one for the impossible, haven't we? A police box? Really? And you just leave us like that? I mean, honestly. It wouldn't take much to fix it. But nooo. It grew on you."
The Doctor turned. There, indeed, was the body of the voice from his past. Golden brown hair, just past the shoulder, deep, light, laughing golden brown eyes, smiling lips, arms crossed over her chest, a bemused expression. "No… no… it can't be…"
"Aye, Doctor, but it is. Oh, the paradox machine was hell, I'll tell you. Painful, and I haven't felt pain like that in, oh, goodness… I don't know. How long has it been? Eight hundred years? Nine hundred? Don't tell me we've topped that."
"But you're dead!"
"My hearts still beat. My mind still works. My soul still survives. Now, why should I be dead?"
"Because they aren't powering your body!"
"So? You know me, Doctor. Never conventional. I've never worked right."
The Doctor had to smile. "Too true. Still… you've been attached to the TARDIS ever since…?"
The girl nodded, laughing. "And why I never showed myself? Well, that's easy. You always had these women around. I mean, honest! But I did like that Rose character. Pretty, too. And Donna was pretty entertaining. Martha was a bit too smart for her own good, but hey. You always liked them brainy, didn't you? And how could you not know she fancied you? I saw it!"
"I loved Rose."
"Aye, still do." Her expression turned brooding. "And what're you going to do now, without her, knowing she's got someone else? Sure, that someone else is you, but still. It's not you."
"Staying on the subject now… how?"
"I told you! My hearts still beat, my mind still functions, my soul still survives! But I'm forever connected to the TARDIS. As long as the TARDIS survives, so do I! Isn't that good news?" she walked up to him, throwing her arms around his neck, hugging him tightly.
"But you haven't aged! At all! You still look the same as you did! Still fifteen-"
"Fourteen, technically. Remember? It was only a few days, and you were already saying I was fifteen, but I was fourteen."
"Okay then, still fourteen, still young, still alive, somehow, but… nine hundred years have passed! How is this possible?"
"Nothing can happen to my body. Nothing. When you took my hearts, soul, mind to fix the TARDIS, it killed me. But because me soul was still alive, and my hearts still beat, and my mind still functioned, somehow, the energy returned to my body. I was… in a coma, in a way. And when you tried to leave me, tried to let me rest, and the TARDIS started to fade… that woke me up. I felt the surge of energy. And it… I dunno, powered up my body. I'm immortal. Not, time lord immortal, and not even Captain Jack Harkness – he was hott, I must say. I really liked him, but then, so did everyone else, it seemed. He fancied you too, Doctor – immortal, but still. Immortal. You can't scar my body, can't kill me. But if you kill the TARDIS, if the TARDIS is destroyed… well, there's be no energy flowing through me. My mind would stop, along with my hearts and my soul. And, well, when your hearts stop beating, and your mind stops spinning, and your soul curls up and looses its glow, what happens?"
"you die."
"exactly. So never turn off the TARDIS. And what was all that, leaving the TARDIS in London when you and Jack were trapped in that satellite? And I couldn't even get into the controls, and that's my mind working them. You were just going to let me die there, weren't you? But you promised. The Doctor and his shadow, his sister, his Sweetheart. Querida. Traveling the skies forever. Together. You'd never leave me. And that's why, when Rose looked into my soul, you see, I took her back, because her mind and my mind overpowered your commands and I could. Because you promised. Forever, Doctor. As brother and sister. Because that's what we were, remember? Siblings. Forever."
"Then how are you not… wrong?"
"Because I'm not a fact, see. I'm a myth. Less than that, I'm just an errant thought, tugging at the corner of your mind. No, I'm still the same species, but I'm dead. I'm just still… animated, I guess you could say. But I've always been that way, I guess. Just a tad off." She giggled. "but you never told any of them. Not one of those girls knows it's me in this thing. You just told them the TARDIS had a heart, a mind, a soul. But never whose it is. Why? I've always wondered."
"What if one of them figured I'd use them for repairs? That the only reason I kept them around, was in case the TARDIS broke down? I'm lonely anough as it is, Sweetheart."
"Querida now, remember? I changed it because I liked the Spanish better."
"Yes, yes, I remember. Querida. And I didn't want to go into the whole story, because… well, you were dead. And I didn't want to think you. About the places we'd been, the things we'd done. And how you… but you're alive! I can't wrap my head around it."
"And we've got quite a bit more wrapping room, haven't we? Then those humans you always pick up. I wonder what Rose would say about me…?"
"She'd like you," The Doctor said absently.
"Why don't we go see?" she said, smirking.
"But… the parallel universe is sealed off. There's no way to… oh. Oh."
Querida grinned. "Exactly, Doctor. When you sealed her off in the parallel world, you created another parallel world, in which she still can see you, but doesn't. And she's alone."
"Would she love me?"
"She's still Rose, Doctor."
"But she's not my Rose."
She sighed. "Gracious. You won't be happy without her, she won't be happy without you… just rip open reality and get her. You did it for me."
"It would cause both worlds to collapse."
"Don't make me, Doctor. I control the TARDIS more than you do."
"You wouldn't."
"Oi, are you willing to bet on it?"
The Doctor paled. "Querida… don't. You can destroy the worlds."
"Aye, I can… or, I can get her to come back to Bad Wolf Bay – do you remember what Bad Wolf means, Doctor? Rose did it, to remind herself to stay with you. I can get her to go back to Bad Wolf Bay, And I can find that one tear that's supposed to be there, which is why you couldn't find it, and go through that, so that she can still go back and forth, but won't be ripping open the worlds and condemning them."
The Doctor thought a moment. "there's a tear, in Bad Wolf Bay, that's supposed to be there, and you know where it is, but I don't?"
"Does it really matter that I notice things you don't? eh? Yes, there is. Now, come on, let's go get Rose."
The Doctor's face split into a grin. "Alright then."
Rose was waiting for them. She seemed to have been crying. "Doctor? Is it really you?"
The doctor walked up. "In the flesh," he said softly.
She looked over his shoulder to the TARDIS, where Querida was waiting. She grinned and smiled at Rose.
"Who's that?" Rose asked.
"Querida? She's my sister, of sorts."
"Doesn't really matter, does it, though? I bug him, he bugs me, we all live happily ever after," Querida called.
"Your sister? A… Time Lady?"
"Nope. Well, yes, but no. but yes. I'm dead, you see. Well, not really. Well, I don't have my hearts, or mind, or soul. But that's a different story. I am the same species as the Doctor, yes. But we're not actually related."
"And of the human me?" the Doctor asked.
Rose wiped her eyes. "He died, not to long ago. Killed himself. The half-time lord thing was too much for him."
"Oh, I'm so sorry," the Doctor whispered. "I never thought…"
"Aye, you rarely think, Doctor. Now kiss the girl and let's get going!" Querida shouted.
"Aren't you tearing a hole in reality?" Rose asked.
"Nope. Natural hole, here. Just big enough for the TARDIS. Querida here found it."
Querida grinned. "Now…"
"Oh all right!" the Doctor called over his shoulder at her. He turned back to Rose, and kissed her.
"Now. Let's get going," Querida said, ducking back into the TARDIS.
"I can come back, though, right?" Rose asked. "I've got a little brother now."
"Of course."