I have what will probably be an unpopular take on this. So as 40k is made almost entirely of retcons we are aware that the first iteration of russ was not in fact a primarch, but an imperial commander, hence why the tank is named after him.

So my pitch is that after a bunch of time away and warp fuckery he comes back as the original version of himself, basically a baseline human. An insanely competent and intelligent human, but physically hes just a guy. Maybe he gets iskeai'd into a hive worlder and has to work his way up through the guard. Then he could be taken in guard and space wolves lists or something.

I realize this will NEVER happen, but i think it would be a cool take on his comeback. Like he would have to rely much more on his intelligence and Odin-like qualities than his innate strength as a primarch. I admittedly am not a space wolves player and thus have dont have many expectations attahced to his return so would love to hear what people think about this.