Tyranids... was already there.... with no sign of a hive fleet around... Would explain alot.

Dammit.... arkona... could be a hive fleet... in planet form..

Everyone buries their war axe and joins the christmas table together to eat universe's biggest meatball. That's what Warhammer 40K christmas is all about!

That would be awesome. The Ultramarines would be considered heretics for maintaining a traitor primarch alive all these millennia and we would have a galactic-scale civil war within a galactic-scale civil war!

But with Alpharius and Omegon, one is a Traitor with the other actually secretly a Loyalist.
So which one would be in Stasis, and where would Guilliman actually be?

Controlling the Imperium from behind the scenes or galloping around the galaxy with Leman looking for the tree of life.

Well, it can be Alpharius or Omegon, it doesn't make any difference for the Inquisition.

What if the primarchs could actually fall in love with women (or men)?

Who says they could not?

Well, if you put aside the rumors of an affair between Dorn and Janetia Krole... Those guys seem to be all virgins

They had lives before reuniting with their father.
Who knows what they did during them.