Question about Guardian novel

[feklar42]

Something that has long nagged at me in the novel is the part of the first arc where they go through the haunted school building. I've read it twice (though the last time was a couple of months ago) and it still makes very little sense to me. I get that the overarching plot purpose is the grandmother's ghost dragging them to save her grand daughter and, thus, finding the sundial.

I always found Shen Wei's role strange. Why would he take them there and then abandon them in the most haunted area?

I've tended to attribute it to being early in a web novel and that the author had not fully fleshed out her plot or SW's character, powers, and background.

But I would be interested in other theories or explanations people might have.