Meet Cinnamon, she looks like an ordinary Eevee on the surface, however due to an accident in her past Cinnamon has developed a slew of multiple personalities within herself.
However, when these personalities take hold, something even stranger happens, Cinnamon herself seems to evolve into a Eeveelution and not only does she go back to being an Eevee whenever Cinnamon is in control again, but can even swap between Eeveelutions by swapping personalities.

Their are a total of 9 personalities inside Cinnamon;

Cinnamon/Eevee
She is a timid, but kind and happy Eevee with a love for baking. She's a prey who really wishes not to be.

Flair/Flareon
The first of her personalities to be developed. He's friendly, acting like a protective older brother.
While prey, he won't go down without a fight.

Jolt/Jolteon
He is an incredibly social Jolteon who loves extreme sports by day, and getting drunk at nightclubs and bars by night. He's pretty open to both eating or being eaten

Vappy/Vaporeon
She is an INCREDIBLY lustful Vaporeon who loves to get wet~ And not much else for that matter.
She is a dominant pred, however, she can be a prey sometimes.

Umbra/Umbreon
A social butterfly who is friendly to almost everymon, he is always eager to make a new friend, and happy in almost any situation.
He roles both ways, either cuddling inside someone or with someone inside him.

Esper/Espeon
A emo Espeon who spends her days waiting and reading. She may look sad, and she is a bit, but she enjoys what she has. She's neutral about being prey, she enjoys being pred.

Forest/Leafeon
A survivalist and explorer who loves going into the unknown.
He goes pretty neutral on being a pred or prey

Glacier/Glaceon
A rescuer, who tends to enjoy research and discovery.
When it comes to being pred or prey she tends to get a little pushy either way.

Slyvia/Sylveon
The bodyguard, though she may look cute, she is easily the strongest and most violent of the group, and is all too ready to kick some butt if they are ever in danger.
A pred, who will make anyone else regret their life if she ends up in their belly.