First serious fanfic on 40k I wrote (already wrote a short crack with the same cross-over once that ended with Galaxia purified and the God Emperor drafted as Sailor Venus' plaything), inspired by "Harry Potter and the God-Emperor of Mankind". Hope it won't suck too much.

by lord Martiya

Prologue: An End and a New Beginning

The God Emperor of Mankind was dying. His last bet, the one that should have destroyed Chaos, was failing with the Golden Throne. He only had scant minutes before it failed and killed him, and Terra was invaded by Chaos. And then, Mankind would be their prey.

He could hear the main Gods of Chaos celebrating, in their own ways. He could hear Khorne laughing and cheering for this most great triumph. He could hear Tzeentch claim it went just as planned without the others calling him out on his bullshit. He could hear Nurgle telling him to give up the useless struggle and stop suffering. He could hear Slaanesh cheering that finally he, the Emperor, would get laid. Still, he couldn't give up so easily. Not after everything that happened. If Mankind and he were doomed, they would simply have to take them down with them.

So he did what he had hoped to never have to do: he connected with every single Human. In that moment, Mankind was one with their God, as strong as they had ever been, a power unmatched by anything before. A power devoted to take down the enemy with them. Khorne loved it, a final, glorious battle. Tzeentch went to fight with annoyance, that was NOT as planned. Nurgle fought back, for his children. And Slaanesh too fought back, for she got off from that. Even their daemons and the minor gods came to the battle, in the hope of defeating the combined might of Mankind and their Emperor.

Mighty warp storms started ravaging the galaxy, wiping out everything unlucky enough to be in their path. Tyranid Hive Fleets were being disintegrated. The Orks were dying. The Tau, the Emperor's other bet, were becoming collateral damage. The Tomb Worlds were breaking with all their content, and so the C'tan. The Webway was shattered, taking the Dark Eldar and the Harlequins with it. The Craftwold Eldar realized what was happening and killed themselves to create Ynnead, only to see their greatest hope betrayed because there was nobody to free it from the Infinity Circuits-so pathetic that Slaanesh couldn't bring herself to laugh at them, in spite of her hate for them, as the Eldar went out with a whimper when the warp storms destroyed the craftworlds and the unborn god inside them. Countless xenos species died one by one, both in the Milky Way and its satellite galaxies, simple collateral damage of a battle between gods they had never heard about.

The battle was hard, even for the Emperor. But he would do it. For everyone who had fallen. For Her. Even if Chaos fought back as hard as they could, he would take them down with him for Her.

And then Slaanesh snatched the corrupted Primarchs and stepped back with all her daemons and followers. It wasn't a might comparable to that of the other gods, but enough to tip the scale. Enough that daemons and minor gods started disappearing, destroyed by Man's last act of defiance.

The first of the great to fall was Khorne. He was the mightiest, and the main target of Mankind's wrath. He brought all his wrath to bear, but to no avail.

Second was Tzeentch, caught by surprise by Slaanesh's action. As he died he could only muse he should have seen it coming. Slaanesh was a divinity of Romantic Love, for twisted as she was, and they knew who the Emperor had been and why he did what he did.

Third was Nurgle. Oldest of the four, the Chaotic God of Decay, Death, Rebirth and even Familial Love let himself fall, to at least spare his followers from the pain.

Last remained Slaanesh, who waited for Man's wrath. She too was destroyed... But as she disappeared she used her last strength to do something, and the Emperor felt himself moving as he heard the Prince of Excesses' advice of "Take down those Tolkien rejects, and most importantly GET LAID!"

Then the Emperor realized his powers were reduced, but he had a body. A HEALTHY body. The body he had when he was still young and had been revived the last time. The Emperor was back being Mamoru Chiba, right after Galaxia's defeat. And he had the chance to do it right from the start.