What was Voldemort's ultimate ambition in HPMOR?

Question

The ultimate fan-fiction Harry Potter and the Methods of Rationality by Eliezer Yudkowsky covers the story of Harry Potter-Evans-Verres, who is raised by Petunia Evans-Verres and her professor husband Michael Verres-Evans.

Harry goes to Hogwarts, and... (considerable subjective-time elapses)...

Meets Voldemort!

Throughout the book, Voldemort (having possessed a certain person who shall remain unnamed for fear of spoilers) is shown to have a dislike/distrust for other people, being contemptuous of them.

With Harry listening, Voldemort details his plans to become ruler of Britain to his Death Eaters:

A cold high laugh. "Ah, Mr. White, the most delinquent of my servants. I have not yet decided if you will survive your punishment. I have less need of you than I once did, Mr. White. In two days' time the Death Eaters shall walk openly. My powers have increased, and I have just this day disposed of Dumbledore." More gasps of shock arose from the Death Eaters, Voldemort paid them no heed. "Tomorrow I shall slay Bones, Crouch, Moody and Scrimgeour, if they have not fled. The rest of you shall go into the Ministry and the Wizengamot, and cast Imperius Curses as I direct you. We are finished waiting. By tomorrow's nightfall I shall have declared myself Lord Ruler of Britain!"

However, Voldemort is also shown to be a master of deception: ^{_{"|Voldemort|" substituted for name of person Voldemort was possessing}}

(|Voldemort| had remarked over their lunch that Harry really needed to conceal his state of mind better than putting on a blank face when someone discussed a dangerous topic, and had explained about one-level deceptions, two-level deceptions, and so on. So either Severus was in fact modelling Harry as a one-level player, which made Severus himself two-level, and Harry's three-level move had been successful; or Severus was a four-level player and wanted Harry to think the deception had been successful. Harry, smiling, had asked |Voldemort| what level he played at, and |Voldemort|, also smiling, had responded, One level higher than you.)

So it is entirely possible that becoming master of Britain was not actually his plan.

Also, Voldemort didn't derive any pleasure at all from ruling:

"Yes," Harry said, his voice almost breaking. "If your goal is to obtain happiness, then doing nice things for other people feels better than doing them for yourself—"

"Do you really think I never thought of that, boy?" The smile had vanished. "Do you think I am stupid? After graduating Hogwarts I wandered the world for many years, before I returned to Britain as Lord Voldemort. I have put on more faces than I bothered counting. Do you think I have never tried to play the hero, just to see how it would feel? Have you come across the name of Alexander Chernyshov? Under that guise, I sought out a forlorn hellhole ruled over by a Dark Wizard, and I freed the wretched inhabitants from their bondage. They wept tears of gratitude over me. It did not feel like anything in particular. I even stayed about and killed the next five Dark Wizards to try taking command of the place. I spent my own Galleons—well, not my own Galleons, but the same principle applies—to prettify their little country and introduce a semblance of order. They groveled all the more, and named one in three of their infants Alexander. I still felt nothing, so I nodded to myself, wrote it off as a fair try, and went upon my way."

So what was Voldemort's ultimate ambition? Was it actually to become ruler of Britain? Or the world? Or something else entirely?

Answer 1

Voldemort's ultimate ambition was little more than to be less bored.

The thing Voldemort fears most is death, so he sets out to avoid that possibility as his first priority. He quite handily deals with that little inconvenience through his use of Horcruxes, then sets out to figure out what he wants to do with his eternal life after that.

He spends some time wandering the world, trying his hand at both heroics and villainy, but finds no real joy in either of them.

"After graduating Hogwarts I wandered the world for years, before I returned to Britain as Lord Voldemort. I have put on more faces than I bothered counting. Do you think I never tried to play the hero, just to see how it would feel? ... It did not feel like anything in particular. ... so I nodded to myself, wrote it off as a fair try, and went upon my way."

“And were you happy as Lord Voldemort, then?” Harry’s voice had risen, grown wild.

|Voldemort| hesitated, then shrugged. “It appears you already know the answer to that.”

^{_{(Bolding added)}}

Finding little real joy in things, he decides to spend his time doing what he can to prevent his eternity from becoming any more dull and tedious than it already is, in the form of attempting to protect the world from a perceived threat. To this end, he seeks to attain political power through control of magical Britain, not because he actually wants it, but because it's the most efficient means to his goals.

"Listen, boy, when I had devised my great creation and come into the fullness of my magic, I thought the time had come for me to take political power into my hands. It would be inconvenient, certainly, and take up my time in ways that were not enjoyable. But I knew the Muggles would eventually destroy the world or make war on wizardkind or both, and something had to be done if I was not to wander a dead or dull world through my eternity. Having attained immortality I needed a new ambition to occupy my decades, and to prevent the Muggles from ruining everything seemed a goal of acceptable scope and difficulty. It is a source of continual amusement to me that I, of all people, am the only one really taking action towards that end."

^{_{(Bolding added)}}

Of course, as one knows by this point, Voldemort was actually playing both sides of the conflict. His original intention was for the persona of Voldemort to be defeated and to take power in a more righteous-seeming fashion, but unfortunately, the image of a hero didn't fit with the one thing that seemed to give him any real joy...

“Why not?”

“Because I still would’ve been surrounded by idiots, and I wouldn’t have been able to kill them,” |Voldemort| said mildly. “Killing idiots is my great joy in life, and I’ll thank you not to speak ill of it until you’ve tried it for yourself.”

^{_{(Bolding added)}}