I have also thought for a time on how easily the Eldar could be recategorized as "Abhumans", due to their outward appearance. It need not be true to be believed, and it brings many benefits to both sides, should both remain true to such an agreement.

I wonder if Horus is going to ever interact with the Horusians.

I think it was a mistake to have the Emperor manifest himself physically into the galaxy to stop Guilliman's beating of Horus. If he could always do this, it opens up the question of "Why has he literally never done this in 10,000 years?" A better way might have been for him to speak through the mouth of Celestine, or to contact Guilliman mentally, or for those assembled in the room to settle things themselves.
A deus ex machina (literally) usually is not the best way to handle things. Other than a few things like this, I've very much enjoyed the fic so far. :P

cool fanfic

Your an amazing writer. I am slowly working through your fanfics and have thoroughly enjoyed what you have written. Keep it up!

A Knight is not a Titan. A Knight is not simply a smaller Titan.

Bit odd thing with Slanesh. I mean for her to manifest so powerfully without an elaborate ritual or the like is very odd for 40k. For the saint to fall so easily as well...Over all smells of " forcing a plot" more than logical progressing of the story. Which I understand is a means to push the Relationship with Horus forward. Still very odd event. It's like an Ork standing up and reciting perfect shakespear out of the blue.

I always found the Emperor's rejection of Divinity odd. There is a difference between being "A god" and "The God". The 40k universe seems filled with powerful warp entities so far beyond normal man they could only be called gods or demons. But it is proven gods can bleed and fall. So merely being "A god" isn't so bad. Now if the Emperor tried to say he was the one and only god... well it might be a bit more of a problem.

Though that said the priest are one of the most corrupt forces in the Imperium from every thing shown in books I have read. Quite often secretly worshiping chaos, murdering and lying to get power. Seemingly more than willing to use the Emperor's good name to gain power and influence.

I find the last part of this chapter pretty funny. I mean every thing I have read and heard about the Imperium's political system Dissent is all that breeds upon Terra. It's filled with some of the most corrupt high end nobles in the galaxy. Corruption, vice, back room deals and backstabbing that can end entire sectors of the Imperium are decided by these men and women of power.

The only thing they ever seemingly agree on is to not agree on anything.

The end of this is more than a bit odd... Yes it's a Primarch but pretty sure "never surender" is in the Imperium handbook against chaos. They give no mercy and no quarter. Surrendering because they caught and threaten your leader seems like an insanely dumb move by every one's part.

Sure the space marines, especially those of his line might falter at the impossible choice. But the rest like the Inquisitor or the saint? To surrender and trust the lies of Lord of Change of all things is beyond stupid.

And when the Emperor rises again, Tzeentch suddenly realizes that what was once thousands of psykers combined into one being has been further combined with a thousand psykers every day for ten thousand years.

Tzeentch: Well...shit.

oh doom slayer i see

The Hand of Darkness does not age things, it corrodes them. And Astartes can't die of age or be weakened by it per-say anyway. Accelerated time effects can, however, due to lack of nourishment within for obvious reasons as well as aging them too quickly for their own physiology to keep up with. Their bodies get exhausted from entropic effects like that of the Hrud, their bodies run out of material to heal and maintain themselves with, their armor's life support systems age and fail, etc.

Why wouldn’t Horus recognize the name of the Death Guard’s Gloriana-class battleship?

Yea,you just win yourself an eldar goddess waifu...