"Albus, I can't just let this go…you know the rules…they are in place to protect the younger races for a reason," said the Doctor, "We have to…"
"But we can't. This has already been established as part of the timeline, including my part as Merlin. I admit using my TARDIS as the castle was a bit much, but she loves the children. You know she's too old to travel anymore. That part of her died…she's stuck here and the children are the only thing that gives her joy and keeps her sane. This…this is my last regeneration…after this, when I die, it's permanent," said Albus, "I spent my last six regenerations here, teaching. First I was Merlin, and then I regenerated into Salazar Slytherin and then into Joseph Hufflepuff, and so on. It's fitting that my last regeneration looks like the first regeneration I spent at Hogwarts. Now…now my TARDIS can die in peace, watching over and protecting the students, guiding them. The curse," he lifted his blackened arm, "will kill me. Even if I had a remaining regeneration, the curse wouldn't be cured; it would infect that regeneration too. It's a Carrionite Time-Lord killing curse. You cannot undo over a thousand years of history. Besides, the founding of Hogwarts School and the so-called building of the castle are fixed points in time."
The Doctor shook his head. He had thought he was the last Time Lord, until he found the Master. Then he thought he was alone again, and then he found Albus. Albus had always been the quirky one of Ramona's family. He was Ramona's favorite older brother and the only one who had not participated in the war. In fact, he had long since been gone from Gallifrey before the war. Everyone simply thought he was dead or stuck in another dimension, as he had always been hopping dimensions. Ramona's family had a gift for specific regenerations; it was rare and hard to control but her entire family could do it, because it was natural for them. He had planned out each one of his regenerations, from Merlin all the way to Dumbledore. And now, here he was, Albus Percival Wulfric Brian Dumbledore, the Headmaster of a school of Witchcraft and Wizardry. A Time Lord, and an expert in Carrionite 'Word' Science, known to some as Magic.
The Time Lords forced them out of the universe, but they couldn't undo their influence. No, the Carrionites had left their imprint on many worlds. Some worlds worshipped them; others were saturated by their 'dark magic' and others, like Earth, had inhabitants with Carrionite genetics. That's why Shakespeare was able to summon them. He was a wizard; although, at that time, he suppressed it because it was the dark ages. No ordinary muggle could have summoned them; there had to be a genetic link to pull them. At that time, Shakespeare was the one with the strongest genetic link. He was a word smith. The right combination of the words, a boost from the Carrionite coven and you've got a Carrionite portal. The Doctor had sensed Albus when he was helping Shakespeare, but then lost him, so he thought it was a glitch. Then when Albus made mental contact, he knew he had sensed him back then.
"So what do you want me to do?" asked the Doctor.
"I want you to teach here after the war, to help the wizard world rebuild. They have the Carrionite genetics and they need your help to control it. You don't have to spend but a year or two making sure things are on the right track. Please, I don't have much time. I've arranged…I've made arrangements for my death. Severus Snape will kill me, as per our arrangements."
"Are you sure Albus? The Sisters of Karn could…" said the Doctor.
"Yes, I know. The Sisters of Karn could give me another Regeneration, but I have lived long enough. Sixteen hundred years is enough for anyone. It's time for me to go, to move on to the next great adventure," said Albus.
"Albus…you can't believe in…" said The Doctor.
"Yes, actually I do. Maybe it's not rational and maybe it's not scientific, but that doesn't matter. I am dying, so I've got nothing to lose by believing that there is another life after this one," said Albus, "Well, if that's all…oh don't worry Thete. My TARDIS has…she's deleted all of her control rooms. She did so after her time engines died; she is incapable of moving through time except the normal way. She's 1200 years old, give or take, and she'll stay that way for a long time. She…she'll stay a castle forever. She's already shunted all of her time energy into making her form permanent and making sure that her inside dimensions stay stable. The only thing that remains of her trans-dimensional engineering is a room called the Room of Requirements; it shifts to whatever is needed whenever it is needed. I think…I think the Artron energies used by the children will keep it that way. I don't know what the distant future holds; who knows what will happen in a few thousand years, but she's got at least that long before she dies. The 'magic' might even help keep her alive longer than that."
"Very well, is there anything else you need…old friend?" asked the Doctor.
"If you see my sister, tell her…tell Romana that I love her and I hope to see her in the next great adventure," said Albus, "and, take this. I used the Chameleon Arch to put a copy of my mind into the watch…it won't bring me back, nothing can do that but…well, maybe, somehow, my mind can help you not be so lonely." He handed the Doctor a pocketwatch and then turned away.
The Doctor shoved the watch in his pocket, and walked away. It would be the last time he saw Albus, as he would die soon. It would not be the last time he saw the TARDIS that was currently locked into a Castle shape and pretending to be Hogwarts, as he would have to come back here shortly after the Battle of Hogwarts to close the time destabilization that threatened to become a rift. He would get to know Harry, Hermione, Ron, Ginny, and George Weasley and the Ghost of his Twin Fred Weasley. He would get to know Minerva McGonagall and he would even get to be the DADA professor for a few years during his 13th incarnation, when he sought to rest for a bit from his travels.