The intensity & scale of his catastrophizing is almost preposterous, though somewhat relatable in terms of what adolescent turmoil can do to a person.
Only weird bit for me personally is that he's otherwise pretty straightforward, whereas I spiral all the time, but I also am way more general when it comes to my overactive imagination, so this very "focused" sort of fantastical freakout makes it feel like it's entirely there to push the plot, rather than a overall facet of his personality.
Small point, and it's only by anecdotal comparison/experience that it even feels incongruent, but.
I wonder if it'll be next chapter that he finds out he is "someone else", or if that plot point will be allowed to hang over his head for awhile before the reveal takes place.