Ok but like hear me out... imagine that, as time goes on, Johannes just kinda... gets increasingly Eldritch.
Like this is a man who sold his soul and didn’t really mind it until it became inconvenient. Sam Winchester who?? Step the frig aside. He’s turned into a ghoul and literally tricked himself to turn back into a human. He’s met Nyarthalotep like,, 4 times?? And lived?? (Probably more or less idk should we include maybe-nyarthalotep Satan??)
This man can’t be defined within the concept of “just mortal”, no way.
And I don’t mean Eldritch like, he looses touch with humanity (anymore so than he already has) or with himself.
Horst will come over one night and. Johannes will just be reading by the fire place, this mass of eyes and tendrils possessing his Shadow and Horst will just be like What in The Nine Realms and Johannes will look up calmly like, ‘Oh? Are you ok?’ And the shadow eyes will blink with him. And it’ll slowly settle back into something more human shaped and normal.
Like. Lil random Very Off Putting things.
Anyhow thats just a thought.