[General] Romance or lack thereof as a personality trait.
Let me explain here. I see a lot of people talking about how all the female characters either have boyfriends or are Hunters and how they feel disappointed that Rick doesn’t seem to be able to write a female character that just exists. She has to be in a relationship or pledged never to have one ever. I’m not saying that’s not true, but I think it’s not just the women. The men of Percy Jackson are also highly defined by their romantic subplots. Almost all of the men of Percy Jackson have romantic partners. The only main male characters without partners for a large majority of a series are Nico, Leo, and Lester and while Nico doesn’t have a boyfriend for the majority of the series, the only books he’s the main character in are focused solely on him and his eventual boyfriend. Leo is single for the majority of HoO, but one of his defining traits is flirting with every other girl he meets and he does get a girlfriend who he’s barely seen without in ToA. Apollo-as-Lester is also single in his main series, but again, one of his defining traits is his flirtatiousness. Personally, I think the whole thing is just Rick falling into that common pitfall of everyone thinking every character needs romance in order to make a good YA book since this problem becomes more heavily pronounced in HoO and ToA which are geared towards a slightly older demographic.