Cheating
In your typical romance story pairing Percy with someone other than Annabeth, the writer chooses to break up Percy and Annabeth by having her cheat on him.
Let's clear something up. I (personally) have no real problem with Annabeth cheating. This is partially because I believe Annabeth is capable of cheating. And partially because to me, all PJO characters are. Even Percy, the very definition of loyalty in the series, could cheat depending on the circumstances. And Annabeth to me is one of those characters that is quite likely to, as I mentioned in Jason/Annabeth.
The problem with a Cheating Annabeth in most fanfics is that, more often than not, the cheating doesn't fit into the story. People rarely make the effort to make Annabeth cheating on Percy believable enough to the reader. Cheating is primarily used as a plot device to break Percy and Annabeth, and to make people sympathise with him, rather than as a way to delve into the characters and explore different possibilities.
If the sole purpose of cheating is to break up the main couple, then just don't do it. Especially if by the end of the story, nobody cares that said characters cheated. This is something you would see in many A/Ns. Writers apologise for making Annabeth cheat but couldn't think of a way to break them up otherwise. I mean, there's plenty of ways to break up the characters without vilifying them or tearing them apart. A simple breakup could work because, as I mentioned in earlier chapters, Annabeth and Percy are teenagers. They aren't necessarily soulmates or something that Percy has to be totally unwilling to leave her. Even married couples divorce peacefully if they've had enough of each other. Percy and Annabeth don't have nearly as much going for a mutual breakup to be impossible. Even dumping him is a better option from the story's point of view.
If the purpose of cheating is breaking the other partner emotionally; well it's not an approach I recommend but there's nothing essentially wrong with it.
In a story where major characters cheat, what's more important is making the readers believe that, yes, these characters could cheat. To do this, the first thing to consider is to pick a suitable pair that might cheat. Typically, in your average cheating fic, Annabeth cheats on Percy with someone that doesn't seem like she would be into; a cocky brat that boasts about his non-existent achievements, who is in no way someone Annabeth would like.
I think the reason Jason/Annabeth make a decent pair for a cheating storyline is because Jason is the sort of guy Annabeth could look to as a fling of sorts behind Percy's back. He has similar traits to Percy, but is a little reserved and stoic compared to Percy's laid back and intimate attitude. It is a pairing which you can properly explore in my opinion.
When you are creating an OC for Annabeth to cheat with, you could create someone similar to Jason, or at least someone that Annabeth could like. For example, Annabeth would enjoy the company of a genius of sorts. It could be a charming god that's also a genius. He could be someone similar to Percy but more… perfect in a sense. You should put some thought into the character instead of going for a generic worthless playboy stereotype you often find in these stories. The guy doesn't even need to be a bad person. He could be a decent man who happened to have an affair with Annabeth. There's many things you can do if you're creative.
Now, I'm using Annabeth mainly as a reference here because she is most commonly found cheating on Percy on the site. The same ideas apply to other characters like Jason, Piper, Leo, even Percy himself.
Percy, I feel, could cheat if a goddess tries to seduce him. You would see plenty of fics where Percy is completely immune to a goddess' advances, even someone like Aphrodite. While there's nothing really wrong with this, I believe people overestimate Percy's ability to resist temptation. Goddesses are extremely beautiful (unless depicted otherwise) and hard to resist if they are playing their cards right. To the very least, Percy should be tempted if they are making advances.
Even with his mortal friends, I think it's possible for Percy to cheat if someone tries hard enough. The right combination of seduction, sympathy and circumstances could result in Percy losing his self-control. Somebody like Calypso, Rachel, or even Reyna in my opinion could get him to cheat. I'm not saying Percy in canon has a huge chance of cheating, it is actually minimal, but a well-written fic can pull it off. And who knows, it might be worth reading.
Last thing I'd mention is that, in most cheating fics, the gods seem appalled that Annabeth or some other character cheated. While it makes sense for some of them to be angry, like Poseidon (for Percy), Artemis, Hera, even Athena, cheating itself shouldn't be a surprising thing for them. Most of the gods are used to cheating themselves, or never committed to a proper relationship. Cheating is such a frequent part of their immortal lives that they should be a bit numb to the idea. All of them acting like cheating is an unforgivable and unprecedented crime isn't just wrong, it's straight up hilarious.
Polyamory/Polygamy/Harems
I am no expert in polyamorous relatationships myself, and find them pretty weird to read. Most of the time, I find polyamory (and harems) in fanfiction to be nothing but wish/fantasy fulfilment, so it's not really a topic which needs to be discussed. But I feel a little inclined to talk about them because of how common they are.
Now, as a lot of you might know, there's certain differences between Polyamory, Polygamy and Harems. Polygamy entails a guy being married to more than one woman. It's different from cheating in the sense that the other wife(s) are aware of multiple relationships. If they aren't then, it doesn't work like a polygamy. In many ways, a guy continuing simulataneous relationships with multiple women (with their knowledge) can be considered polygamous, even if there is no marriage involved.
Polyamory is more than two people having a mutual relationship; all or most of them with each other. Harems are more along the lines of ownership, where all women involved are owned by the man. Most harems would count as polygamous, but some could go into the realm of polyamrous with the women having relationships with each other as well.
In general, I'd recommend not going for this approach unless you started with the intention of writing a polyamorous/harem fic. A lot of writers suddenly add more characters into a relationship with the MC, and people (like myself), would be negatively surprised by the sudden change of direction. Also, changing from mono to poly halfway through rarely works from a storywriting point of view, because the characters usually aren't presented like they would be okay with multiple partners. The relationship tends to feel unnatural, fake and a major case of wish-fulfilment.
If you do want to write a poly fic, build it up in a way that it is a possibility for your MC (Percy) to have multiple partners. People should be able to expect it coming, since most of them might be weirded out finding out later in the story.
If you are writing a polyamorous relationship, the first thing to keep in mind is writing characters in a way that they are likely to indulge in it. Then, pick characters who fit together. For example, Artemis - especially a truly chaste Artemis that likes Percy for his loyalty - does not fit into polyamorous relationships; it takes effort to fit her into a normal one let alone a polyamorous relationship. If she will be in one, the third is more likely to be a hunter like Thalia or Zoë. She most likely wouldn't be okay with sharing her first, only love with anyone else she doesn't even like. Such as Aphrodite.
Percy himself being someone who values loyalty, makes the chances of a polyamorous Pertemis being believable even more unlikely. I recently read a Percy/Artemis/Aphrodite story, and while the writing wasn't bad by any means, none of the characters made sense. They were all acting weirdly OOC (in context of the story itself), and the main reason could be pinpointed to both Percy and Artemis not being the sort that would like Aphrodite romantically. The compatibility of all characters involved should be considered before and while writing one.
For harem stories, I will say that they aren't particularly interesting to me. Most of them are just a guy venting out his fantasies as Percy rather than any real attempt to make the story interesting for the reader. They rarely ever feel like PJO fanfiction since none of the events seem to belong in it. The characters are labels, no work put into actually making them feel like they are the same people we are familiar with. Most just have a stupid premise where Percy has to bang all of them or something for his own safety. The worst ones I've read are the ones where Percy gets powers which he can use to get into any girl's pants. I understand why anyone would come up with an idea like this, but for so many people to do so is just weird. Like, if you do want to read or write some smut, wouldn't you enjoy it if the MC actually was a charmer instead of relying on some bs powers to seduce girls? What's the fun in reading a character who girls are attracted to just because he has "special powers"?
If you are interested in the harem stuff, then I'd suggest trying out Tales of a New Olympian. It at least puts some effort on coherence and worldbuilding.
Now, polygamous relationships are a little different from the others. There is a little more room to be creative compared to polyamorous ones since not everyone involved necessarily likes the others and probably views them as rivals. These can make for interesting stories if you write them well enough. The context is more important when writing these. Did the MC fall for both women before getting into such a relationship? Is one (or all) of them forced/arranged? Did he get together with the one after the first was out of the picture for some time? How are the relationships between the women (or men if you feel like it) and the MC and with each other? Ask yourself all these questions when writing these fics.
I would conclude by saying that, only write a poly relationship if you started out with the intention. You can try to fit one in the middle of the story but chances are you will ruin the romantic aspect. Especially don't switch to poly because a reviewer suggested you to. Fanfiction is primarily for your own satisfaction, I understand. And if you want to satisfy yourself, there is nothing wrong, But if you want to write quality stuff, at least put some thought into the stories instead of going with what you think is hot, which is what most people seem to be doing in these stories.
Romantic Encounters
One thing that surprises me in the PJO fandom is that, while writers have tried every single pairing possible (like Percy/Chaos), I have yet to read a story where Percy has multiple romantic encounters throughout the course of the story. Sure, there are smut fics where Percy has sex with every female (and sometimes male) character possible, but that's not exactly what I mean.
There are no stories (that I'm aware of) which follow the typical "hero" stories where the MC journeys across the story's world and has multiple romances with the characters; each to their own merit. These romances don't necessarily need to come to a "happy ending". They don't need to go all the way sexually. They don't even need to take off, just a sort of tension for a period in the story. Your typical "hero" protagonist usually goes through all these relationships over the course of a book or series.
In PJO itself, Percy has three romantic encounters: Calypso, Rachel and Annabeth who was there from the start. Yet even the longer stories in the fandom usually focus on a single pairing. Or at most two, with one barely given any attention. The ones that have multiple pairings are poly, with Percy being in many relationships simultaneously, instead of changing the pairing for an arc or two.
One story which tries to work multiple back-to-back relationships is Rise of the House Neptune, even though the second pre-planned relationship, Percy/Bianca, wasn't that well done. The pairing wasn't bad, but it felt a little forced and dull.
I personally believe it could be interesting if people try to write stories where Percy has many potential partners, and multiple relationships that are all different in their own way. They don't all need to be sexual, or stories of "true" love, or even get off the mark. Just multiple romances that are unique and differ from one another and happen over time in the hero's life.
P.S. This wasn't a cliche or something like that, but I thought I might share the idea. And this idea doesn't have a lot to do with Romance stories, where the pairing is predetermined. This section is mainly for long Action/Adventure stories where the romance isn't the focus but is still there.
Arranged Marriage/Forced Relationship
The Arranged Marriage/Forced Relationship trope is one that I believe has potential for interesting stories. The idea to put two characters who aren't in love but could make a couple into a forced relationship is good. It's not great, true, but it is good enough to be given a try.
I understand that a lot of people believe that people should only marry whom they love, and couples that didn't love each other before committing don't work at all. This sort of thinking tends to seep through the mind when reading/writing these stories. Approach these stories with a clear head or else you might never enjoy them. Arranged marriages might not be ideal, but they aren't terrible by any means, and as such the chances of them resulting in a decent, healthy relationship are almost the same as marriage by choice. The only difference being that the best relationships built on love tend to be more passionate and happy compared to those that weren't.
The main problem in these stories is that the couple seems to fall in love almost immediately. While it can happen for some people, if you are writing a story about a couple that wasn't in love, it makes sense to build it up. Have them understand each other, learn to love each other and deal with the problems that can arise from an initially loveless relationship. It would be very similar to building up a normal relationship, except that the two have to try to make it work even if they don't want to. That would probably add more conflict to the relationship compared to a normal one.
Here's a general layout. Considering that the stories are very likely to take place in America, the couple would be averse to the idea at first. At some point, both, or one of the parties could feel like they should try to maintain a proper relationship. This could be at the start, in the middle of the story after some major event, even at the end of the story. Soon the ending would come in, and the relationship should reach whichever point you wanted it to at the start. Of course, by no means is this very vague layout something you need to follow. You can pull in your own ideas and be creative. But most stories about a loveless relationship would follow this general idea.
You could mix in old lovers on the side. They could be a point for the other to feel insecure of. Or, they could simply display how both partners feel about the relationship. If Percy is forced to be in a relationship with someone other than Annabeth for example, Annabeth could be given special attention in the story. The other girl could feel jealous of her if she is slowly accepting Percy, or simply sees him as a matter of pride. She could just ignore her if she doesn't care at all about the relationship. Percy still being in love with Annabeth could be an important subject in the story.
As I usually say for romance in fanfiction, the pairing doesn't need to have a happy ending. Ideally, a story will end happily with the couple in love. But it is not necessary if you want to try something different. It could be an unhealthy relationship from the start; it could end on a sad note. The relationship could be a more friendly bond. It could end up being an open relationship. One of the characters could eventually find someone else. In fact, the pairing you are trying to build up doesn't necessarily need to be the one that's arranged. There's many ways to deal with this kind of story instead of a complete romance.
Now, arranged relationships in PJO fanfiction would happen for one of the following reasons. It could be prophecy based, political, or part of the culture. Quite frankly, I'm a bit surprised that no one has written a story where the overall culture among demigods is one of arranged marriage on behalf of their godly parents. It could be an interesting concept for romance in a story that is primarily not romantic. Or is; that could work too.
For prophecy based stories, I can't say much. It all really depends on how good the prophecy and plot is since prophecies can be about anything. A very good prophecy based relationship is Percy/Artemis in Forbidden Child as I've mentioned before. I think it is a good story about a girl (or maiden goddess to be specific) going out to find love because she has to. In that case because of a prophecy.
Political relationships on the other hand would need a little more understanding. Random characters would not have a political relationship because random characters don't always qualify for them. If your story is more of an AU, it would help to define the characters in a way that it could be understood for them to be in relationships for politics. Revenge of the Duchess does a really good job at that.
In a world that isn't very different from canon, there are very few candidates for a political sort of relationship/marriage. For Percy, the candidates would be Annabeth for an Athena-Poseidon alliance; Thalia, Artemis, Athena (or other daughters of Zeus since there are so many) for Zeus-Poseidon; Hestia, Demeter, Artemis, Athena or some other goddess in as an Olympian "reward" for the hero who ascended to godhood; Reyna for Roman-Greek; Hylla for Amazon-Greek/Roman (based on the circumstances). Some people use Zoë for Othrys-Olympus. Villains could be used as well. In addition, Jason and Annabeth could be used for the Greco-Roman alliance as well.
Now Annabeth with Percy for an Athena-Poseidon, there's room for creativity here. How the relationship will work depends on Annabeth and Percy's initial relationship. Are they enemies/rivals? Are they just friends? Or do they already have some feelings for each other? I've seen this usually in Mortal AUs and Ancient AUs, but not within the context of the PJO world. It's not the best for the trope, but it's not bad.
With Thalia, I believe there is room, and the relationship could be made very toxic. Lots of bickering and fighting over who's boss I guess. I haven't seen that much to comment on.
Reyna and Percy's relationship in this case could be a little dull honestly, but it would be interesting to see someone try. Reyna did find Percy to be attractive in canon, and the way she approached him was very similar to a political relationship. I imagine that the two forced into a relationship might be initially cold or indifferent to each other as opposed to being toxic and conflicting. It could be interesting in context of a plot that supports it.
Hylla on the other hand could be more exciting. The Amazons are more authoritative and love men who submit. In the case of a political relationship, that is not necessarily going to happen. It could be interesting to see a man approach them on equal footing. Or no. That too wouldn't be uninteresting as long as you put the effort in.
With the maiden goddesses, forced marriage is a little off considering that the entire reason they swore to be maidens was to prevent themselves from getting married. But since the stories could be interesting, there's no harm in sidestepping that fact. It's not a very important thing to keep track of in fanfics, though I admit that is pushing the boundaries of the established world. It is possible for the maiden goddesses to be married if Zeus in the end decides so.
Athena could be very weird for some people being Annabeth's mom. I honestly think the trope could be interesting for Athena/Percy although there is not a single story about the two. The premise of the pairing would be pretty toxic, I imagine. She obviously wouldn't like Percy, and the feeling could be considered mutual. If Percy and Annabeth were (or are) in a relationship, it could be interesting if the writer handles it well, although that would be going in the "wrong" direction.
Artemis, I believe, works really well in the trope. Being the character she is, a story about Artemis getting forcefully married to somebody she holds some respect for, but still not liking the idea itself could be interesting enough. While there's quite few forced Percy/Artemis stories out there, most rush the love from both parties. I'd say that a forced relationship between the two could be more fun to read if both or either one of the characters are reluctant initially. Percy being more reluctant than Artemis could certainly be a believable and interesting twist depending on how you write it.
Hestia might not be that interesting to read, but is a suitable one if you want quick fluff. Demeter might not be interesting at all considering that she hasn't even interacted with him. Other goddesses I wouldn't recommend for the same reason but some could be interesting. Even Hestia and Demeter could be interesting at the end of the day. All depends on how you approach the story.
Zoë for a Titan-God alliance I have seen once or twice I guess. The problem with it is the context of Zoë's character. If she is a Hesperide in a God Percy AU, she's going to be a rather different person. It could still work, but I doubt it will be interesting. Once she becomes a Hunter, she has already sworn allegiance to Artemis, an Olympian, so it makes no sense for her to be a factor in a deal, unless at some point she decides to rejoin the Titans (wow, that idea came up somehow).
The villains that I suppose could end up in a political marriage with Percy for whatever reason, are Khione, maybe Hecate or some traitorous goddess post TLO (with Percy as a god in any of the cases). Hecate herself wouldn't be particularly interesting in my opinion because her character wouldn't fit in the Arranged Marriage concept really well.
Other than that there might be villainesses out there that could make a good pair with Percy or another character if you feel like it. Maybe Medea for Jason in an AU. That could be interesting.
Please note, I am not talking about some kinky punish the evil goddess sort of story. There is no one stopping you from wanting to do this but I am simply talking about an alliance of sorts. Punishment in this case could be unwarranted and unwelcome.
