𝐒𝐄𝐂𝐓𝐈𝐎𝐍 𝐂:
Twilight fanfiction aid
𝐯. A polyrelationship between a pack member, OC, and a Cullen

TBH, I have not read much Poly Relationship in fics or published books. I haven't explored the genre thoroughly yet. I read a werewolf polygamy book back then, and I loved it. I don't really wander around those kinds of tropes. Still, I do respect people who love to read and write because we all have different preferences for what we like to read and enjoy.

I'm not a party pooper, but let's mention one of the fairly obvious reasons why I think it would not have easily worked in CANON, but if it's FANON, we're going to ignore CANON. Of course, it would have worked.

Shifters & Vampires HATE each other. So do Werewolves and Vampires. Werewolves are different from shifters. They literally loathe each other's existence. The shifter's reason for existence is to eliminate the cold ones that are a threat to human society. It goes against every ounce in their nature to like each other.

Guys, this isn't some enemies-to-lovers trope. It's literally pure loathing and spite without any romantic progression.

In Eclipse, their common ground was to protect the humans of Forks from the newborns & protect Bella. Otherwise, it would have stayed exactly the same. When Renesmee was born, the pack wanted to kill her because the baby was an abomination, a "monster." There is no way that both creatures would be willing to co-exist with each other in CANON.

A vampire in every story is territorial in nature. They are possessive. But, let's also consider that many vampires have lived for centuries; immortality has initially become very boring for them, so they had considered polygamy or reverse harem as well—with other vampires. Or they can choose an eternal soulmate with whom they could spend their eternity. Vampires choose their mates, and werewolves are destined to be with their mates, like imprinting for shifters. It depends on what vampire legends you follow. Many different relationship models for vampires and other supernatural beings have been created by literature and the media.

Let's use Jacob, Bella, & Edward, for example. The movie version. Because Bella didn't give Jacob a time of day in the books, her only focus was Edward and Edward only. The men in the movies are jealous of each other; Jacob is vocal about it, while Edward is more internal about it. Edward is jealous because Jacob could give Bella a normal human life, but he couldn't. Jacob hates Edward because Bella chose Edward after leaving her for months and because of her willingness to turn into a vampire. But it's going to be weird, too; imagine that if Jacob, Bella, & Edward are in a poly relationship, then Jacob imprints on Renesmee, LOL.

Besides, a poly relationship wouldn't have worked on them anyway. Do you think Edward, who hasn't had sex for a century, would try polygamy? Who's a conservative catholic? Who also has the mindset of a man from the early 20th century? CANONICALLY, anyway. I know a lot of people back then for Bella to just end up with them both—had fanfictions for them, too.

Then Sam, Leah, and Emily are another example of the shifter. We all know that Sam & Leah were together, Sam shifted, they drifted apart, Emily arrived, and then Sam imprinted on Emily and broke up with Leah. He didn't consider being both with Emily & Leah, even though he still loves Leah because his only imprint is Emily.

The concept of mates & imprints is that you only have one destined/fated mate. But of course, if you know, werewolves' reverse harem works differently in published books, too. Cause, you know, as I have said, there are different types/preferences when it comes to media and literacy.

So it really depends, but CANONICALLY, a poly relationship between a pack member, an OC, and a Cullen would not have worked. (I believe if you want to follow canon rules, it can still apply since Smeyer added Mormon characteristics in the books, and they did practice polygamy back then for 50 years, but it's forbidden now.)

If it's a poly relationship between vampires & humans, it would have worked, and a poly relationship between shifters & humans would have worked. But if you mix them together, it would not have worked. They would kill each other before they even got together in a relationship or even made progress.

In FANON, I know it would have worked because it's Fanon, duh; you can do everything.

The shifter and vampire would make an agreement because they both share the same love for the human, and all they want is for the human to be happy.

So, how would you write a poly relationship of shifter x OC x vampire?

You'll completely ignore the canon rules and the laws of vampiric & shifter nature and write them as having to share the same motivation of finding common ground for their human mate. (just like any supernatural polygamy book)

The shifter in this has a lot to sacrifice. They will willingly stay immortal by shifting all the time so they don't have to age and live forever with their partners. They will completely give up the perspective of having a family—only if the OC wants to turn into a vampire. You can also write that the OC & Shifter had a child and then turned into a vampire, but the problem is there will be a chance that the child won't be a shifter, only a human—you can literally do whatever you want.

You're a fic writer. Do what you gotta do. I just stated some obvious things that would make a poly relationship shifter x OC x vampire difficult in the first stages of their relationship, but if you want to make it possible, do it! No one is stopping you. It is after all Fanfiction.