DISCLAIMER: I don't own Doctor Who.

"Thank you." The Doctor walks over to me, leaving a house that belonged to his old companion. An old man, in tears, is standing in the house, giving the Doctor a salute.
Donna was the next companion he had to leave behind.
He opens my door and enters me, the TARDIS, disguised as a blue policebox.
I can feel his sadness, the next companion he had to leave behind.
But this time, he is feeling even worse.
Why not? A lot of things have happened in the past hour.
He left behind all his companions, all the ones he had in this incarnation, apart from Astrid Peth.
Rose Tyler, the only companion he truly loved. He left her behind in the parallel world, the world she belonged. Perhaps leaving her hurt the most for him.
Martha Jones, returning after she abandoned him first, now engaged to Tom Milligan. She was going to work with Torchwood, or with UNIT... I don't know anything about her future.
Donna Noble, who inherited the Doctor's mind. But, being just a human, she couldn't take it and the Doctor had to wipe her mind completely.
She was one of the best friends the Doctor ever had.

"We're going to 1936." He sais. He wants to travel a while, and I let him. Of course.
I'm telepathic, so I can tell what the Doctor thinks. He thinks about River Song, hoping he will meet her somewhere in the future. He has a companion to meet in the future, he is guaranteed to travel with somebody.
She told the Doctor it that way. I can tell they will have a strong bond, but it will end bad anyway. That's a Time Traveler's problem.
I'm traveling through the Time Vortex, trying to be easy on my Timelord. He is alone, fully alone in the entire universe.
The ones who do understand him all have someone else.
The one who understands him the most is no longer in this universe.

He thinks about Sarah Jane Smith, an old companion whom he could meet again, together with her son Luke. She had to go back to him and the Doctor didn't even bother trying to bring her back travelling with him.
He thinks about Captain Jack, the one whose true name is a mystery, the one who can't die. He, too, can't go back to travel with the Doctor. He has a team to take care of.
He thinks about Astrid Peth, who travels the universe now, with only her atoms. She has died, but the Doctor recalled her.
She can't travel in full form anymore, because of the Doctor. Because she sacrificed herself.

He thinks about Adam Mitchell. It was his own fault he was abandoned again. He could've changed the past significantly, he could've caused a major paradox.
But, in his time, the Daleks were unknown. Perhaps the 2012 after the Dalek invasion is different. I'd love to go there, but the Doctor sais 1936. I'm fine with that as well, if he feels like it.
I can tell his mind has just crossed the most severe subject of this adventure.

Who revealed the Doctor's soul.
Is it his fault all the people sacrifice themselves for him? Is it his fault everybody thinks he should live? Is it just the people's fault because they sacrifice themselves?
Harriet Jones, Lynda Moss, Jenny... all of them sacrificed themselves for the Doctor. Why? What does he do to deserve such sacrifices?
A mystery that can't be answered.

At last, we arrive into 1936. He steps outside of me and walks around a bit. He's still sad, but I can understand that. He walks around, meets some people, says hello and things like that. Things the Doctor does.
While he walks around, he pretends to be cheerful. But his thoughts betray him for me. To me, he can't fake who he is.

I love him.
Of course, not the way Rose Tyler loves him. I love him the way a brother loves his sister, or the other way round. I'm sure he feels the same way.
But his love for me is stronger than the love he has for Rose Tyler.
That's because I'll never leave.
Things can go strange, parallel worlds can be pulled open, I can get to run a team for myself, or start working for UNIT. Well, I could if I was human.
But I won't.
Because, all I want is one thing. I want the Doctor to be safe, I want to travel with him.
After all, companions can come and go. Peri Brown, Sarah Jane Smith, Melanie Bush... they all leave sometime. But I stay.
I'm the only one who can be called the permanent companion.

He orders me to go to 1928. He's all done now, he wants to see another time. That's fine with me, I can feel the Doctor's depression, so I just do as he says. I tend to be a little stubborn sometimes, but now is not the right time to be like that.
He thinks of the Abzorbaloff, of his similarities with it. The fact that, once you touch the Doctor, you get absorbed. He doesn't like it, he doesn't want it, but he's got no choice. People just want to be either his companion or they want to sacrifice themselves for him. Or both.
But I don't need to be sacrificed. Because we will stay together.
I'm the TARDIS, and I'm the only permanent companion the Doctor will ever have.
And no matter what, my love for him and his love for me will never change.

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