I'm just gonna come out and say this... I really like your Demon!Ryan, but I fully support the Demon!Shane theory. He's a very powerful demon. So, powerful, in fact, he's the reason him and Ryan haven't found any ghosts/demons. They're all scared of him. As for Ryan, I think Ryan might be possessed but doesn't realize it.
Haha I don’t worry I’m not like against demon!Shane or anything.
I just wanted something different.
In my world, my story, which I can’t really find any time to write right now...
His dad is literally goat man (just based off the small joke he made about his dad being named “Steve” as well).
But he had to be given up to a human family to take care of him. He actually poses as his uncle and looks scarily alike (obviously).
Ryan slowly comes to realize “woah shit I’m actually half demon lol what the hell” but he doesn’t want to do anything bad
As for Shane, he’s being possessed! He doesn’t know it, Ryan doesn’t know it (until his dad tells him) and then he’s like “woooahhh that makes sense” because Shane, while in possession, can for some reason enact things that are demon-like
More to come but I don’t wanna spoil too much