It's said in Ashes of the Damned that all of the 8 player characters were sought out by the Warden because their Spiritus had been "touched" by a being or artifact of great power relating to the Dark Aether. This includes both our Requiem crew from BO6 and the nu-OGs.
We know the specifics behind what happened to Requiem and Dempsey, and there's a few clues as to what happened to Takeo, but as for Nikolai and Richtofen we've got pretty much nothing.
I was wondering if anyone else has any ideas on what they think could've happened to either of the two, or if there's any dialogue I missed that could paint a clearer picture. Thanks!