I honestly see little-to-nothing of fanon!Locked Tomb in the books, though for me that was an excellent thing since I found fanon!TLT and specifically the way Gideon/Harrow was talked about actively offputting. Like ... without getting too into spoilers this is a series very much about the ways in which traditional romantic love is and should be deprioritised imo, and I think going into the books (well, at least HtN) not wanting/expecting Gideon/Harrow made it much easier for me to enjoy them.

...Though obviously none of that would've helped if disliking Harrow on her own would've been enough to put you off them lmao.

/has a lot of feelings about these books for someone who STILL has not finished GtN because of said memes in the prose. HtN has many fewer of them, fortunately for me.