Great premise

I just need to write it down. It was great premise. Simple clopfic turned to something amazing. Unfortunately author wanted to write simple clop and this premise overwhelm him. So he deleted his story. I had to write summary of it down, so it won't be forgiven.

It was shameless clop. Really bottom of barrel, but written without orthographic errors, so it was a plus. Human turned alicorn. He had sex with every mare, even married Cadance. Turns out, there was a ancient law, where when alicorn mare is pregnant with alicorn, who is not her husband. That alicorn must fight her husband for a mare. And it was important, because pregnant mares NEED father of foal, to be nearby to deliver healthy baby (magic from father support pregnancy or something). And this duels between alicorns are until death or dismemberment, means until one of them get his dick and balls, horn and wings rip off. But it is ok you see, because alicorns can regenerate any limb. Also there is some magical bullshit so the law won't be ignored. Also beaten stallion can be changed to mare, or abandon duel fully in favor to changing to mare (some alicorns don't want to fight, because they can die, so sometimes changing to mare is safer option for some alicorn stallions). Most duels end with dead (remember, curbing alicorn population, and if father of gestating foal die, the foal also die ans sometimes also a mother [foal siphon magic from mother, and often there is not enough magic for two ponies to live, that is why father is needed nearby]). Also hornless and wingless alicorn can die of exposure (alicorns lived in times before discord, where there was not really a civilization, and why should be, when you are a powerful alicorn, unless you lost your horn and wings, then you are easy target for hydra or chimera before they regrow). Turning to mare regrow limbs instantly.

Now.

Who was Cadance husband? Shining. Shining wasn't alicorn, so his jewels won't regrow.
Also Cadance cheated on him, because she wanted a baby (normal ponies can't impregnate alicorns). Also human turned alicorn impregnated Twilight Sparkle.
So this law was written when alicorns banged alicorns, and also has other things mainly to prevent alicorn overpopulation. It needed some suspension of disbelief, but it was good enough.
So normally alicorns don't marry and bang normal ponies, because they are not atracted to them. Just simple biology preventing from ruting creatures, that can't get you pregnant. Something like normal ponies just don't have good enough hormones to even get alicorn mare horny. And alicorn mares don't have heats without alicorn stallion nearby. But Cadance as a element of love is more horny and geared for marriage, So she married Shining. Law wasn't even considered paring between alicorn and normal pony.

So there is Shining.

Just happened to be a victim of ancient law. And he was cheated by his wife. And his sister was impregnated by same stallion, who impregnated his wife. And this stallion also impregnated bunch of other mares (some slight jealously from stallion biology).
And now he has to choose: fight to death, or change to a mare. Did I mention that loser changed mare have to be in herd with winner?
So Shining chose fight to the death. Cadance wanted him change to a mare, because she love him. Protagonist didn't kill him, but had to rip his dick and balls of, and horn. Shining put out a decent fight (he was fueled by many emotions), but he was not alicorn and lost.

Shining get really depressed.

He lost his wife (now she was married to human turned stallion) and his position (he could not be a prince, because his marriage has been cancelled, because he lost and marriage between alicorns overrule marriage between pony and alicorn)
But there is a kicker. Cadane and Shining were trying to have a foal and fund research to find a way to have a foal. Because Shining was loving Cadance to the death, he COULD impregnate her (and only Cadance, because she was avatar of love). There was a researcher, who didn't know about duel and just provide Shining and Cadance with this fact and very simple and easy solution to make this happen.
Shining was not happy. He had a tantrum in a middle of a court (where Cadance and human turned alicorn was having court), that has him threw in a jail. Cadance was trying to console him and reconcile with him, but Shining was too hurt and without his gonads and horn. He was just a victim of unfair law. Also this law could be amended, but it was a long process, and duel could not be postponed. Celestia and Luna was too young to pay attention about it on Starswirl lessons, so they simply forgot until it was too late. Cadance simply wasn't aware of it.

So it happens that there was Sombra's horn nearby (some magic mumbo jumbo, but enough to be believable). And Sombra ofered revenge to Shining. And Shining took it by aplying Sombra's horn onto his own. Some magic happen and Shining break from prison by destroying whole wall. Several of them. And he teleported to Sombra's hideout.

So now Shining is a legitimate threat. He is powerful and is wielding magic not known by alicorns. Sombra was a prodigy, he could take one alicorn, but could not take two (Celestia and Luna in the same time). Now he/they have double the magic pool that synergize with itself. Also he fueled by negative emotions, like Nightmare Moon. Nightmare Moon was one pony, Shining and Sombra are too, and it means, there is a power of double Nightmare Moon available. Shining was also a prodigy, not as a Twilight, but his shields are superb. And Shining could love to death, so also he could hold grudge and hate to the death. He was really a big threat now.

And Shining has a legitimate grudge making him very good villain. Also there was some Sombra backstory trying to legitimaze his grudges, but wasn't good enough to me to remember.

So now human turned stallion has to train to fight Shining, because he could not now overpower him with magic power alone. Also he really just know how to rut mares, and not how to fight (he was kinda selfish and shortsighted person as a human). Also his good ruting is not because of his skill, but just because of his hormones.

And in the background Shining is having internal fight about dominance, like Lich King and Arthas in Warcraft universe.

And that is where story has been cancelled.

Author just wanted to write shameless clop about impregnating mares. But after a dozen or more chapters premise above crystallized. And author simply wasn't good and passionate enough to continue premise above. He just wanted to write some cheap clop.

So he deleted story.

It was a great story.