Khonshu's Avatar Choices
What if Khonshu is attracted to avatars that are mentally ill or have a predisposition to mental illness?
In one episode Harrow asked Marc if Khonshu chose him as his avatar because his mind was already broken or because it would be easy to break. This makes sense.
Khonshu is obviously a manipulative being. He held Marc's life over his head like a toy so he could get Marc to do what he wanted. Having past trauma would make doing something like this easier for the god.
Khonshu also probably likes to go after people with military experience because of their ability to fight, like Marc. It would give a solid explanation as to why he's fond of Marc and Jake, but would rather have Steven go away. Marc's time in the marines would give him combat experience and Jake at least knows how to use a gun, but Steven... not so much. Layla has also been shown to be a competent fighter, so it would make sense that Khonshu could see her as a fallback if Marc and Jake didn't work out.
Many soldiers and veterans also suffer from PTSD, making their minds "easier to break"
Khonshu appears to favor Jake over Marc and (duh) Steven, so it's also possible he found a way to "tweak" things so that Jake would end up fronting more often, or fronting at the most crucial times (i.e. when Harrow was about to yeet Marc's soul in Episode 6). By doing this, he would be worsening Marc and Steven's DID, thus figuratively "breaking" their minds even more.