This is where the climax happens, which should be extremely action-packed, but I haven't worked out what it actually is, yet.
But during the climax, we learn the truth about why the Time Lords on the High Council really wanted to take Dawn and kill her husband. And why they interfered with established history to do so.
It wasn't just politics or making Jenny look bad, after all.
Remember that when Dawn had helped Seo cross all those universes and rescue the Moment, she'd been pregnant with her third child, Will. At the time, Dawn had been nervous about this, for the sake of the baby. Remembering Amy Pond.
Seo had reassured Dawn, by saying that the child wasn't conceived while traveling through the Time Vortex, and that — anyways — she and Dawn weren't traveling through time, they were traveling across universes.
On Gallifrey, the Moment had warned Seo that rescuing her would mean sacrificing someone that Seo never wanted to sacrifice.
Here's the full truth about what had happened, after the Vengeance Demons wiped out the Time Lords and took over Gallifrey's technology:
Seo's reasoning was along the right path.
When Gallifrey was destroyed and history rewritten by the vengeance demons, at first, the Doctor and Buffy had both been exactly the same way as we all know them, in their TV shows and in this series. Kind, compassionate, and heroic.
The Doctor had not been in the same universe as Gallifrey, and had survived because of that. However, he soon realized what had happened to the Time Lords, and how the Vengeance Demons must have gained control over time.
The Vengeance Demons had used Time Lord time scoops, but the Doctor had managed to evade them (with the dexterity he'd used back when the Time Lords had used such scoops). The Doctor, instead, landed on Earth — where he found Buffy.
At that point, Buffy was on Earth, leading a resistance group against the Vengeance Demons in the hopes of regaining planet Earth for humans.
It took a little while for the Doctor to get Buffy's memory of the original timeline back. But he did so. When he did, Buffy had told him all about Dawn's little escapade into another universe in order to save the Moment. And how Dawn had been pregnant at the time.
The Doctor had remembered Amy Pond, and put two and two together.
"The Time Lords might be bureaucratic busy-bodies," the Doctor told Buffy, "but they still don't wipe people out of time just as a political power-play. If they did something as horrible as wiping out an entire family, it's because the Time Lords saw something. Something that'd happen generations from now, because of that child. They wiped out all three of Dawn's children, just to make sure that future never came about."
"How can we be sure?" Buffy asked.
"If the vengeance demons have taken the Time Lords' place," the Doctor replied, "then Dawn's distant decedents will eventually threaten the vengeance demons, now that time's changed. If I'm right… the vengeance demons will be trying to hunt down Dawn's children and kill them — just in case."
Sure enough, they soon discovered that the Doctor was right. The Vengeance Demons were now trying to kill Dawn's children.
The Doctor and Buffy saved Dawn's kids, then placed them into the TARDIS. The Doctor sent the TARDIS away to where the Vengeance Demons would never be able to find it.
He'd wanted to send Buffy away with it, too. But Buffy insisted that if she went, then the demons would know something was up. Better to stay here and find some plan to stop all the Vengeance Demons from destroying history.
They did try, but the Vengeance Demons figured out the plan and changed time so that it failed. Buffy died, the Doctor regenerated (12th to 13th Doctor). Since the Doctor was weak after the regeneration, they were able to capture him and catch him up in a temporal bind.
"We've kept you alive for one purpose, Doctor," D'Hoffryn explained, "and one purpose, only." He turns on the Doctor, making him suffer horribly. "Where is the TARDIS? Where are the children? What did you do with them?!"
The Doctor says nothing.
In actuality, the Doctor had pulled a temporal trick with Dawn's children, making it so that when they entered his TARDIS, they effectively disappeared from history. People could remember them, but as a kind of dream.
That meant the children were permanently outside the Vengeance Demons' reach.
"If you don't give us the TARDIS and the children, Doctor," D'Hoffryn warned, "I can make your life a living hell."
The Doctor didn't tell him anything.
So D'Hoffryn and the other Vengeance Demons subjected the Doctor to all kinds of tortures and torments. Trying to force him to tell them how to get to the children, or just give them a hint.
But he didn't.
"You don't want all the children," the Doctor guessed. "Just the third one. That's the one you think might beat you."
D'Hoffryn begrudgingly admitted that the Doctor was right.
"Let me guess," the Doctor says. "After the Time Lords met Seo, they figured out — if she was from the Axis, there was almost certainly a copy of her, back on Earth, with fewer powers but still the ability to unlock universes. A few Time Lords decided to scoop up Dawn, to use her to get the planet back to the correct point in space-time. In our universe. And the rest of the Time Lords agreed... because they'd foreseen something worse, and knew that wiping Dawn out of time would prevent it."
This was right enough.
"The Time Lords knew that Dawn's third child," D'Hoffryn said, "was born... with certain genetic variations. It wasn't quite like your own experience with Amy Pond and the Silence — after all, without an influence like Madam Kovarian to bring these genetic variations out, the variations simply remained dormant in Will's DNA. As they will in his decedents' DNA. And in their descendants' DNA. And so on. For many generations."
"But eventually, those traits will become dominant," the Doctor guessed.
"The Time Lords foresaw a day," D'Hoffryn agreed, "far in the future, when one of Will's descendants... would have the ability, cunning, and skill to invade the other universe, wage a miserable war against the Time Lords. And destroy them utterly."
And, of course, when the Vengeance Demons figured this out, it was obvious what the implications were. If there were no Time Lords around... this same decedent would rise up and destroy the Vengeance Demons.
"But you know this," D'Hoffryn says. "That's why you took the child away and hid him. You programmed your TARDIS to alter his genes and bring out those genetic variations, thus making him powerful enough to destroy us."
"Did I?" the Doctor asks. "Doesn't sound like me. Harming innocent children?"
D'Hoffryn points out, however, that the Doctor would have done it because he'd know it could be undone, later. Distract the Vengeance Demons enough, and the Doctor could double back and save Gallifrey from the catastrophe that had destroyed it. Eliminate the Vengeance Demons' grip over history.
Everything would be undone. Will would be a normal child, again.
"Nah, that's not like me, at all," the Doctor said, playing dumb. "You're just playing for time."
Of course, the Doctor would not give in and tell the Vengeance Demons where his TARDIS was, no matter what the Vengeance Demons did to him.
The torture went on for a long time.
Then, one day, it stopped. And the Vengeance Demons seemed to forget about the Doctor.
The Doctor only found out why when the Moment showed up, inside his cell. To visit.
"And here I was, thinking you were good," the Doctor says to her. "All that convincing me to save Gallifrey... was it all for this? So you could give the technology to your chums?"
The Moment says something enigmatic. About the greater good, perhaps? Or being forced into a situation where she has to comply?
The Doctor, however, is beyond furious. "Don't push me off with something like that!" he snaps. "They'd never have been able to absorb all that knowledge, if there weren't someone else around who could explain it. Someone... like you."
The Moment doesn't deny this.
"You made me keep the Time Lords alive, just so you could take them down, later!" the Doctor roars. "And steal their technology! A willing collaborator for a bunch of demons! Doesn't matter if you're sentient or not... you're still just a weapon, deep down inside. All you want to do is kill."
The Moment then tells him that the Vengeance Demons have decided to force him to talk.
And she's decided to help them.
By changing him.
"It won't work," the Doctor warns her. "Change me, and they'll lose all hope of ever finding out anything."
"I know," says the Moment.
She grabs hold of him, and he cries out as she sinks deep into his timeline. And begins to reach out for that paradox.
So that's what really happened.
I don't know how much of that would have actually gone into the story.
Another thing the readers discover is that the Moment was the one who gave the Vengeance Demons the ability to combine their powers into a single large crystal.
Thus, giving Seo the ability to make her wish in the first place.
And condemn Gallifrey.
(Story plot continues in next chapter.)