It was ironic, really; his identity as Merlin had troubled him for so long, on and off, during his seventh incarnation, that he'd actually been relieved when he'd dealt with it all during the early days of his eighth body. That mess with Muldwych had been complicated at times, but after the last time he'd seen the other Time Lord, the man who was once the Doctor was satisfied that Muldwych was nothing more than another possibility in a similar vein to the Valeyard; he existed somewhere in the future, but he wasn't going to be his future.
Right now, however, as he studied the man who'd been Merlin in this universe, lying in silent repose on the table before him, he almost missed his own brief period in Camelot. It had been complex at times, but it had been a happy experience in its own way, helping to guide Arthur where he could and mitigate the damage that other Time Lord had done.
What he'd asked this man to do was almost the exact opposite of everything he'd tried to help Arthur create in Camelot.
The Ancients were one race he'd never really had time for- their final fate of Ascension was so boring that even most Time Lords hadn't been interested in it; they at least had enough life left in them to step up when the fabric of reality was at stake even before the war- but he still had to admire the subsequent efforts of the Stargate program to understand their technology while keeping it secret from the rest of the world. UNIT had still dealt with most of the threats Earth had faced from alien intelligences in this era, but the SGC had done a good job most of the time.
Their skill was the main reason he'd never stepped in to the war against the Goa'uld earlier. As dangerous as the Goa'uld had been, they were fundamentally little more than Osirian experiments that got out of hand but never had the same power as their creators, and the war against them had helped humanity grow and prepare to take their place in the wider universe.
The war against the Ori, on the other hand, had nearly shattered all the hard work they'd put into helping this part of the galaxy heal from that oppression, to say nothing of it costing a great deal in lives, resources, and culture. The Goa'uld had deserved everything that would happen to them, and killing the Wraith was one act of genocide he didn't want to resort to when some of them had shown that they would be willing to at least consider alternative feeding sources to humans, but if the Ori learned of the existence of the Milky Way, the SGC would learn nothing more interesting than various minor mythological secrets that didn't really matter in the long term.
With that in mind, the man who had once been the Doctor had set out to track down where the Alterean known as Merlin had been left in secret, awakened him to appraise him of the situation- while exaggerating the imminence of the danger posed by the Ori- and then sat back to watch him put the Sangraal together, using a few medical packs he'd acquired for the purpose to keep the old man alive long enough to complete his work.
He wished that he could have saved Moros's life completely, but the only way to accomplish that would have been to allow him to Ascend again, and when he'd brought it up at one point Moros had made it clear that he had no interest in giving Ascension a second go.
The old man had accepted his fate so long as the Ori were dealt with, but it still frustrated him that he could do so little to save people in this body; the best he could do was eliminate the bigger threats…
Maybe this whole plan was just his way of trying to 'redeem' himself for destroying that twisted matrix by taking out a race of egotistical higher-dimensional monsters, but he was saving a whole galaxy from a false religion that did nothing but sustain those who should have died long ago; unlike last time, the only people dying now had lived full lives already.
As he inserted the last crystal into the Sangraal, he carefully carried it into the TARDIS before he entered the latest coordinates, setting his course for the distant galaxy that the race known as the Ori had adopted as their own.
Genocide was a harsh crime by any standard, even if it was genocide of a group who had simply taken a different approach than the destruction of an entirely distinct species- at heart, the Ori and the Altereans were still the same race- but the Sangraal wasn't even technically killing anything; it just rendered them incapable of doing anything on this plane of existence.
Whatever awaited them after the device was activated in the heart of their galaxy, the man who had once been the Doctor didn't know and didn't care; after setting themselves up as gods and keeping an entire galactic population under their thumbs for centuries just to boost their own power, he had no sympathy for the Ori.
As he watched the wave of energy emerge from the device to spread across the galaxy after the TARDIS materialised, the release spreading into levels that even the TARDIS couldn't quite detect, he could almost find it beautiful if he didn't think about what it was doing any more than he had to.
AN 2: For anyone wanting clarification on the timing, assume that this is set just after Anubis's defeat for the SGC; the Wraith will still be an issue, but now the Ori are completely off the board, and that's that.