Nimrod

After accepting the offer to come to 40K, this guy sobered up and called himself Nimrod as he thought about how to get out of this hive city. Although there aren't restrictions on leaving, Imperial planets with hive cities rarely have easier places to live on the planet, and the lack of legal enforcement means he could be killed just walking around. Thus, Nimrod decided to just say FUCK IT. Nimrod grabbed a piece of metal and made a spear, killing some gangsters to get a gun as he made his way out.

Once outside, Nimrod realised he wasn't getting off this planet, let alone doing anything meaningful in this world. Once again, Nimrod could only do one thing: say FUCK IT. With his arms to the sky, he shouted in an open plain: "HEAR ME DARK GODS, HEAR MY WRATH, PRAISE BE TO KHORNE'S STRENGTH, PRAISE BE TO TZEENTCH'S POWER, PRAISE BE TO NURGLE'S BULLSHIT REPRESENTATION OF NON-INFECTED ECOSYSTEMS, AND PRAISE BE TO SLAANESH'S PUSSY. GIVE ME STRENGTH, AND I, A MAN OF ANOTHER WORLD, SHALL GIVE YOU ALL THAT YOU DESIRE FROM THESE MORTALS. MAKE. ME. A KING. MAKE ME FREE, AND THE WORLD SHALL BE YOURS. I WON'T BE YOUR ****, BUT I SHALL RETURN YOUR INVESTMENT 10-FOLD BEFORE WE ARE RID OF ONE ANOTHER."

The gods hear all prayers; they don't necessarily care, but they derive power and are, at least unconsciously, observing all their followers. So, when they heard Nimrod through prayer, the gods' interest was piqued, and that's when they realised it. His soul was different; Nimrod's soul was present, but it wasn't related to the Warp in any way. On its own, he presented as much of a danger to the Warp as Blanks, or probably a little less. Still, the fact remained that he was unique from all other life in the galaxy, because even the Blanks were related to the Warp in how they denied its existence, specifically through anti-soul power. At the very least, to taste such a soul would be a unique delicacy, one that might not dissipate like other souls, but one that might not go to the Warp when he dies.

Thus, the gods sent Nimrod a message, asking what else he could offer them besides momentary strength. In response, Nimrod offered his mind, not to corrupt, but to see. All he asked was that Isha be his guarantor, stopping the gods from twisting or bending his psyche. To this, the idea of learning about their world from another's 4th-wall knowledge tantalised them, and so they accepted, hoping to use this knowledge in their plans. What they didn't know was that Nimrod was one of those "the Devil's in the details" kinda guys. Using Isha, Nimrod used her power to scar and repair his brain, allowing for fake and believable memories to be implanted.

What they saw was a bastard who hadn't actually read a 40K novel, nor a 30K; he was just one of those extra observers. There was certainly knowledge to gain, but nothing that would ultimately change the course of history. It was interesting that certain points were not known to man because of a lack of writing, as well as several theories, but these were useless things. Still, a deal was a deal, and they wondered what a "transmigrator" might do in a land he knew to be pain incarnate.