Hraesvelgr and elidibus also have taken on other souls with few side effects, especially if you disregard the whole mad primal thing. Hydaelyn as well, but that’s weirder with eating them for energy. I don’t know, there just seems to be something going on with soul assimilation and/or modification that I’m missing a key part of. I’m not expecting it to turn into the matrix 3 either, but that golden divot prophecy mentioned souls too I think? Maybe it’s just a reference to another game, it’s not like souls is an entirely novel territory for the series.