In the World of Sword and Magic as Space Marine

The warp is a vital tool to us, a means of communication and transport. Without it, there would be no Imperium of Man, for there would be no quick bridges between the stars. We use it, and we harness it, but we have no absolute control over it. It is a wild thing that tolerates our presence, but brooks no mastery. There is power in the warp, fundamental power, not good, nor evil, but elemental and anathema to us. It is a tool we use at our own risk.

By Warmaster Horus before his fall into Chaos. 

------------

Nine Weeks Later, 

William's fleet continued their travel through the warp for nine weeks. At first, the sensation of the warp travel made William's back chill as ice and vast souls within Warp made him paranoid. But as time moved forward, William adjusted to some normalcy to the point he didn't feel any issues afterwards. 

Due to the continuous need of navigator's psychic sight, William forbade his librarians from using blank abilities as it would interfere with navigation itself. The ship and fleet in general is big enough to house everyone to have comfortable living spaces as well as enough food from ration packs to monster meat from the New World to feed the whole population for a dozen years (If rationed extensively.) 

William's typical day is spent on managing fleet meetings and daily communication with the rest of the companies to make sure they are battle ready while preparing strategy when they reunite with Imperium. 

Meanwhile, Rana spends her time with the fleet officers for daily operations for the fleet civilians such as food, medical and other essential things to make sure travelling through warp is livable. Sisters of Battle and Space Marines on every ship do their best to make their presence known as much as possible which makes potential security breaches as low as possible. After all, ship shielding, blessing of the holy oil, and water couldn't one hundred percent hold back the warp from making small breaches, leading to minot daemon attacking ship crews and personnel. Overall, William's fleet is making somewhat safe travel compared to horror stories where Imperium has to go through the warp. 

------------

William and Rana's personal chamber. 

"I swear, the daily meeting is becoming tiresome and repetitive. I start to think we barely have time for ourselves." William places his datasheet on the table while he turns around to see his wife, who just put down their son, Henry, into STC Pod. Even though Henry didn't show any signs of his blank or Primarch ability, William was certain that Henry is more powerful than himself, who is genetically engineered with Emperor's tissues. 

"We have to be understandable, not just us but everyone is working hard to make sure we make the journey. Just yesterday, one of the Battleships went into lockdown due to rioting in the lower level. It seems the influence of the warp made people turn into a Chaos cult. Thankfully, Ship security forces and a few of my Sisters managed to cleanse them before they went out of control." Rana said as she fixed Henry's necklace pendant back into its original position and closed the pod. The pendant is made out of pure gold adamantium just like his outer layer of the pod is made out of. 

"I just got updated on that. I was surprised that it was Sisters who handled the situation before Lord Creed or Cain did. Will the Sisters conduct the service for the loss of causality and blessing to reinforce the lower level of the ship?" William said as he poured two cups of wine and passed one to Rana. With grace, Rana accepted the cup and was about to speak when something unexpected happened. 

Behind William, a tear in space ripped in force and before William, who was still in his power armor (Not terminator) could notice Rana's surprise expression, a massive boney hand with an eye attached grabbed the Chapter Master. Before the mysterious hand could yank William through the ripped warp portal, Rana cast a holy protection onto William, protecting him from madness which is the realm of warp. In William's point of view, his view went from Rana to darkness in a second as the only light source was the protection that Rana managed to cast before he got pulled into somewhere else. 

'I know this sensation…' William thought to himself but it was pointless as the culprit revealed himself in front of Wiliam. Darkness slowly dispenses into dark and light blue as the massive hand that held William twists itself to face the owner of the godly hand. 

"How? We are protected by a gellar field. How did you manage to break through the field?" William said to the owner of the hand. The beings who possess multiple hands and eyes spoke in multiple voices that followed one after another. 

"You think minuscule things such as a gellar field would protect you? You are travelling within the warp itself and I'm the Warp! This is nothing but a small portion of what I can do." Tzeentch sneers mockingly and proceeds to shout in rage. 

"You piece of shit. You cost me everything and for your action, I will teach you a lesson you will never forget." Tzeentch said in anger and irritation. For some reason after the closing look, Chaos God of Change looked worn out and exhausted as his body showed multiple cuts and was covered in feathers mostly likely belonging to birds. Tzeentch continues to speak. 

"Because of your action, all of my bird collections got destroyed by fucking Skarbrand! When you sent Skarbrand into the Crystal Labyrinth and not only he destroyed all my bird cages but he managed to eat half of them. Not to mention he shattered the majority of crystals when he attempted to find his way out from the Impossible Fortress." Tzeentch said in pure anger, half close to what Khorne goes through on morning traffic without his Recaf. 

"When did I send Skarbrand to your… Oh, that's right." William quickly realised what Tzeentch was talking about. The three way battle between Khorne, Slaanesh and his own legion at the capital city. The mysterious warp signature that William ordered his Krieg to bomb the area after the knight body slammed the Skarbrand into the building. At least one mystery was solved for William's mind but this didn't help him as Tzeentch is now more furious. 

"You are telling me you didn't know. You didn't know that you sent brute into my thoroughly organised realm this entire time? That's it, I'm going to make you pay not with blood but with daith itself." Tzeentch brought out his second hand to hold William. Just as Chaos God of Magic attempted to do something, a golden light shone behind William and Rana's spear pierced one of the Tzeentch's eyes. 

"You will not harm my husband even if he is wrong. Only I'm permitted to do that." Rana, the Emperor's Living Saint ripped through the closing warp space in force and made her appearance into Tzeentch's realm. Fully armed from top to bottom, Rana brightens the Tzeentch's blue realm with golden light, which disturbs the Chaos God from acting his punishment unto William. 

"Damn that Anathema's light. I can't see shit." Tzeentch cursed as the light of the Living Saint blind him. This only lasted a few seconds as Rana's initial light eventually died down and once again blue light of the Chaos surrounded everything including Rana and William. 

'The light? It actually did something to him.' William thought to himself and quickly went into his inventory to find a certain item. Meanwhile, Rana recalled her weapon and went into an attacking position with her shield front while her golden wings expanded from her back. 

"You are not from my reality or Anathema's so I don't know what you will do next but I can make a guess with this." Tzeentch summons another warp portal next to him and pulls out something metallic using one of his free hands. The moment Rana and William saw what was in Tzeentch's hand, they both panicked as Henry's pod could be seen. 

"You son of a bitch!" William shouted in pure rage and pulled out his item he was looking for. The one thing that holds the light of the Emperor of Mankind, the Spark of Astronomican can be seen from William's right hand and with all his might, William throws it at Tzeentch's face. The moment the sphere of the Emperor's light hit Tzeentch's face, it exploded with gold and white light that blinded even Rana's vision temporarily. 

For the second time, Tzeentch experienced pain and blindness. For the Chaos God of magic and change, the blindness blocked him from seeing all possible futures and paths he wanted to take. 

"Screw all of these for once. You will suffer first just as I intended." Tzeentch spoke with madness in his voice and proceeded to grab William's left and right arm with both hands. Without any hesitation, Tzeentch ripped William in half and to everyone's horror, it wasn't a physical mutilation but rather separation of body and soul. 

William's Astartes body begins to separate from each other but instead of two Astartes bodies, the second body appears to be different in physical size. The whole process only took less than nine seconds but due to massive backlash from Tzeentch's magic and abuse of force separation, William lost his consciousness while William saw his own body faint while he was in another body. A body of a mortal man and his original from the Earth before he was sent to the New World. 

"What did you do to me? Did you, did you just Alpharius Omegon me?" William (Mortal) spoke in a panicking voice but this didn't help at all as Tzeentch smiled in the most sinister way possible to what he just did.

"Why, of course. I know of your origin and I decided to give you back what makes you a you. Just like Alpharius and Omegon who went from one body and mind into two, I simply separated your soul into two. One for Astartes and one for a puny mortal. In a sense, both of you are William, same memory and soul. Hahahaha" Tzeentch began to laugh but didn't last as Rana appeared and slash Tzeentch's hand that was holding Henry's pod with a fury. 

"You will release my son and my husband! What in the Emperor's golden throne?" Rana demanded with rage and wrath of the Living Saint but she paused for a second as she saw unconscious William and a mortal man in hands of Tzeentch. 

"You are still here? If you want this then you can have it!" With irritation, Tzeentch threw the baby pod directly at Rana, who quickly recovered and withdrew her weapon and shield to grab the pod. 

Rana extended her golden wing of energy to stop the pod from going further but it was pointless as Tzeentch opened his third hand to open a warp portal right behind Rana and Henry's pod. 

"Hahaha. Be lost in the warp forever with your son!" Tzeentch laughed and with that Rana and baby pod went into the mysterious warp portal. Meanwhile, William, who is in mortal body, quickly grabs one thing that could distract the Tzeentch while he figures things out. He needs to find Rana and his son, Henry. He also needs to merge with this other half if he wants to survive, that is if he can figure that out. 

"Hey, bird nerd with optical issues." William shouted to get Tzeentch's attention which he did as one of the Tzeentch's eyes focused on William. William couldn't tell if he could make the throw as distance seems to be changing as if space itself was folding and expanding. But with no options available, William decided to make his gamble once and for all. 

"Eat space bugs!" With that said, William once again threw an object towards Tzeentch but since he is now a mortal man, the throw wasn't that impressive as it was before. Still, the object William threw managed to open and from within a massive number of Leviathan hive fleets appeared from the Tesseract cube. All heading directly at Tzeentch's head.

"What the fuck is this?!" Tzeentch said in surprise as he didn't expect this kind of action coming from William. The hive fleet appeared between Williams and Tzeentch and due to warp space folding and expanding, Tyranid fleet managed to fully appear from Trazyn's Tesseract cube and ready to devour anything that was in front of them. 

"Get them off of me! My magic, why can't I feel magic around me?" Tzeentch panicked for a second as he didn't realise that Shadow in the Warp from the Splinter Fleet of the Leviathan is preventing the very warp within Tzeentch's realm. 

With Shadow in the Warp suddenly making its presence within the warp, Tzeentch's domain and warp itself began to degrade as Tzeentch's hand began to disappear into real space. Thankfully, Astartes William who is still unconscious reappeared into his personal chamber where he was pulled out from before. But for mortal William who doesn't have the original destination where he was pulled out from ends up travelling through the warp time and space. 

Fortunately, mortal William still had Rana's holy protection to protect him from the warp itself but his luck was all out as he had no way of navigating through the Sea of Souls. In the end Tzeentch got his revenge as he managed to separate William into two individuals and separate his family through space and time, permanently. 

As William travels through the warp as a mortal man, a mysterious being in the shadow smiles and laughs in chuckles. Using ability beyond black void, the being redirect mortal humans into different times within the warp. With laughter of his own joke in the making, the mysterious being just gave himself a new toy to play around and another opportunity to mess with four Chaos Gods. 

[What makes a great story? A tragedy! Hahaha! Bazinga.]