Discord dumped Tirek onto the floor of Canterlot's throne room. The centaur shrank back before the combined might of Celestia and Luna, vastly unprepared for this encounter. Upon not being attacked, he recovered somewhat, turned, and buttonholed Discord. "What? You… what? How could you work for them?"
Discord flicked the finger away. "Tirek. You haven't changed a bit."
"You have. You've gone soft."
"On the contrary, I've gone smart. You are still as dumb as a rock. Strong, but dumb with a capital S. You don't even know why I would never have helped you win, ever. You don't even know what I want."
Tirek gibbered, then finally, "Chaos, of course!"
Discord nodded. "Some, yes. Let's do this with music. Do you know music theory?"
Tirek glanced to the two irate princesses, and based on their expression he decided that it was in his best interest to keep Discord talking. "A little."
"Here is a very low C." The floor turned into water and a standing wave was set up across the room, one peak alternating with one trough, and a pitch rang (the standing wave was very much slower than the pitch). "And here is an octave up - low C. Half the wavelength. If you go to a third the wavelength, you get G - a perfect fifth. A quarter the wavelength, the next C, and you're up a perfect fourth from that fifth. Very boring, harmonious stuff. But if you go to a fifth the wavelength, you get an E. A major third. And from there, the sixth of the wavelength, you get… the minor third as you go from there to G. The original six elements of harmony, if you like. C, C, G, C, E, G. So close to a genetics joke, but not quite."
Discord gave a flashing smile to the princesses, who looked on in bemusement. Tirek was utterly lost.
"We can round it out with the whole step as up a fifth down a fourth, and the half as up the major third and down the minor third. Now you have dissonance. Discord. And that's all you need to create… this."
The water subsided and in its place, a panoply of Discords sprung up as a jazz band, a string quartet, a vocal trio, a guitar duet, and a yovidophone solo, all playing different songs very well.
Discord let it run for half a minute, letting one dominate, then another.
"You can even add in other notes and do this. This particular piece was made by splitting the octave twenty ways instead of twelve."
Bizarre, otherworldly, ear-jarring music sprang forth. Tirek covered his ears and Luna summoned earmuffs, but Celestia cocked her head and paid close attention.
"I like this, and harmony can learn to like it too, just as I've learned to find the discordant elements of this…" The string quartet resumed for four measures, ending on a dissonance. "… even if I can't live on it."
A flourish, and rubbing his claw against his paw. "Now, let's have some pure chaos."
The musical Discords shattered into tiny multicolored fragments which flew around the room as a blinding snow and hissed, filling the room with both audible and visual white noise.
Discord held it going for ten interminable seconds before shouting over it, "Boooring!"
A single tone began to be audible as Discord went on, "What's this? It's you. Our good old friend, low C. One. All alone." The tone grew and grew, and the noise softened and faded away until that pure pitch was the only thing audible; the light fell from everything else, leaving only Tirek visible.
"If white noise was boring, this is a thousand times worse. And that's where you would end up, eating everything, absorbing it, just you, you, you. No room for anything else. Ultimate power, last, final power. The fundamental. No harmony, no dissonance, no discord. One note. One voice. One opinion. Forever. Unison. Not even an octave to keep it company."
The note faded, and the light returned to everything else. Tired more than anything else, Discord said, "Tirek, we did have good times, but only because you never got close to winning. Your victory would be my death. Then, you were a threat to ponykind, yes. Not to civilization as a whole. But now, with this many ponies? You really would be able to grow too strong to be beaten. You actually could win. Which means we can't work together any more. You might be funny as a running gag, but let to have your way? No."
Tirek's eyes widened and he hollered, "I was a running gag? You're the running gag!"
"No, I'm improv. You? You'd get some power, fiddle around feeling amazing, then be beaten by a more skilled enemy, shrink down, and run away. It was hilarious until you actually got good enough that you won against a serious challenger five times in a row. Then it became so much clearer that you had no idea what you really wanted, and it was just sad."
Tirek narrowed his eyes. "I do know what I want: more power!"
Discord yawned. "Yeah, you're just a low C after all. But maybe not forever. I have an idea. It goes like this. You give back all of the power you've stolen, and I lend you a thousandth part of my power. More than enough to get by in the world. You'll be decently strong. If I feel you grabbing any power from anyone else - and I will feel it, don't doubt it - you had better have a very, very good explanation, or you will wish you hadn't. And you'll be giving it back even if you had an excellent reason."
Tirek grunted. "What do I do with this power?"
"Find something to live for that isn't gathering power. Become an interesting person. More harmonious, and more chaotic at the same time." Discord turned to the princesses. "I hope this plan works for you?"
Celestia looked to Luna. Luna frowned, and declared, "Far be it from me to deny a second chance, but I question whether he is at all interested in actually changing."
Discord cocked an eyebrow far enough to disconnect from his face. "I wasn't when Celestia freed me, either. It took an epiphany. It took my realizing I actually was free, having no fight to win, no strategy I had to execute. Nothing to do but choose what I wanted. And, that what I wanted had room for something else besides myself. And a bit of time past that. I didn't say it would be instantaneous or quick."
The princesses silently conferred, and nodded.