What a Jason and Leo led book (or series) could look like (Hint think Orpheus and Eurydice mashed with Cupid and Psyche):
I KNOW THIS IS A LONG POST BUT STICK WITH ME HERE!
This is how I image Leo and Jason could realistically end up together in the books in a way that doesn't involve changing anything Rick has already written, ie no change previous relationships or any of the plots of the previous book series.
The overarching theme of the book/series would be choice, working of self esteem problems/self acceptance, and the feeling like you have control in over your own life and decisions.
Beginning of the Book/Series:
-The book/series would start out from Leo's point of view. I think we would learn about more of his current struggles including: him still grieving Jason, his relationship problems with Calypso, him not sure if he really enjoys mortal school like Calypso does, and potentially some issues with his fire powers which he had previously believed he had full control of.
The Downfall of the Calypso and Leo Relationship:
-At some point in the beginning Leo and Calypso would officially break up. I believe this would be because :
1) Leo's deteriorating mental health
2) Calypso being in the real world and seeing what normal relationships look like, realizes that what she feels for Leo is more similar to familial love. She discovers that the Curse didn't actually mean she had to always fall in love romantically but rather fall in love in any capacity, (including familially). I believe she would explain that she tried to be romantically involved despite this realization because she cared so much for leo but realized that it wasn't working out or healthy for either of them.
3) They both wonder if the only reason he wants to be with her is because he feels like she's the first one who really gave him that kind of attention and if it had less to do with it actually being Calypso he was in love with.
4) Calypso wants to try being single for awhile and rediscover herself before returning to have relationships.
(I personally like this because I think that one issue people tend to have with recent Riordan series is that it feels like someone needs to have some big reason to be single, like joining the hunters. But this would fix that that because she would just be choosing to be single for herself for awhile while not swearing of relationships forever).
Leo would be upset about the breakup at first but then he would have some introspection and realize that maybe it was for the best. I think he would even feel slightly relieved since it was lowkey stressing him out before.
Leo would call Piper about his breakup and learn from his talk with her that she had broken up with Jason. While he knew that she had moved on with Shel, he hadn't realized that her and Jason had actually ended things between them. I think he would feel very mixed about this because while he understands Pipers reasons, I think he would feel bad for Jason (hoping that he knew how loved he was he died) and some small part of him feels slightly happy that their relationship didn't work out. The latter part he instantly feels bad for and pushes down (to be later brought back up and reevaluated)
Leo Trying to Figure out What He Wants for His Future
Leo struggles more than he thought he would at Mortal school. And while there are aspects he loves about it and things he really enjoys about Indianapolis, something feels off. I think there would be a lot of frustration for Leo in this.
I believe it would make sense for him to regress a LITTLE (emphasis on a little, we don't need a reset) to be more like the version of himself that we saw on the Argo II, at the beginning of this book/series. This would be caused by his grief and current personal struggles which I think would make sense narratively. Leo would feel frustrated that, while he was able to outsmart death, someone like Jason died before he got the chance to live the life that he only just started to be able to choose for himself.
Leo, due to general grief, ptsd from his own sacrifice and insecurities may be struggling with his fire again. I think his control of his fire could be an allegory for self acceptance. Before the end of HOO he had almost full control but his control is waning and he has to relearn how to use it. This would be a great opportunity to showcase the raw power of his fire in a similar way Percy has insane abilities due his control over water.
I think Jo and Emmy would help him work out some of his feelings and guide him to make choices for his own happiness.
Leo would decide that he wants choose his own path forward and that Jason also deserved that. Somehow (whether through something Jo and Emmy said or from another Demigod friend) he would get the idea of bringing Jason back from the dead, afterall didn't he also cheat death?
During either the winter or summer solstice the God's invite the 7 minus Jason to finally honor them now that everything has been relatively calm. It is during this celebration that Leo asks to bring Jason back from the dead, shocking everyone.
The Gods can't simply bring back Jason though, making Leo remind them of the story of Orpheus and Eurydice. They point out that Orpheus failed. Leo brings up that he still had the opportunity though and if he was given the opportunity, then he wouldn't fail.
They come up with either a quest or just offer him trials closer to what Psyche went through in order for him to bring Jason back to life. (this opens up a call back to the Cupid seen from HOO in the future).
Hera is a big supporter of Leo in all of this because she wants to see Jason brought back to life. I also think Apollo who feels guilty for Jason's death supports this plan.
Leo has to go through a series of trials to bring Jason back to life, just like Psyche had to go through to prove her love for Cupid. This could happen just over a course of a book or over the course of a series.
Unlike Psyche, Jason and Leo would have to go through some of these trials together. This would help develop their relationship which would ultimately result in a romantic relationship as well as it would help Leo more with his self esteem as Jason would help encourage him and show him that he is good working in a team.
I think we could begin to get point of views from Jason, which would help develop him more. It could give the reader insight to his time in the afterlife and him processing his own life. I think we could learn that he felt like in the afterlife he learned more about himself and what he wished he could do, making him want more than ever to be alive for so he could live the future he dreams of. (Yay development for Jason)
Throughout the trials, Leo regains his control over fire with the help of Jason and even learns new techniques. I would love a moment of Leo being powerful and realizing that people are looking at him with awe and fear the way they looked at Percy and feeling in disbelief that anyone could see him that way.
Even though Jason would be with him for a large part of the Trials, I think it would be a great way for Leo to process his grief (which he always ran from as a kid) and for Jason to see how his death impacted others and to finally feel like he has somewhere to return too that he really belongs (with Leo).
I think the final trial could be the Orpheus and Eurydice style of leading Jason out of the underworld. It would be the ultimate test of Leo's own self-esteem to trust that someone would follow him/choose him.
Both boys struggle with belonging and I think that a book/series could tackle that issue for them as well as provide the opportunity to go into the concepts of choosing your own destiny (as both boys were kind of previously ponds in the world of gods).
I think that this wouldn't take away Jason's sacrifice because they would still struggle immensely to bring him back to life. I also think one or both the Boys should be partially disabled after these trials. 1) more disability rep is always great 2) I think it still shows they are sacrificing something, that bringing someone back from the past has a price.
Because both Orpheus and Eurydice and Cupid and Psyche have a sight related aspect with Orpheus turning back and seeing Eurydice and Psyche looking at Cupid when she was specifically told not to, this story needs something sight related. The sight aspect is what made me connected the two myths together in the first place. (Maybe Jason loses his sight or something idk)
I feel like we need more than just an Orpheus and Eurydice style plot to develop the relationship between Leo and Jason to make it fully romantic, Hence the Cupid/Psyche style trials would allow for this opportunity to get them to that point (plus uncle Rick likes to use many myths simultaneously to create his storie). This would also be a fun mash up of greek and roman myths, just like Jason and Leo are a mashup of both greek and roman, since Cupid/Psyche is Roman and Orpheus/Eurydice is Greek.