One idea could be that the werewolf girlfriend has to hide her true nature from the human world but slips up during a full moon. Another could be a love triangle where a human and another supernatural being both vie for the werewolf girlfriend's affections. Or perhaps she's on a mission to protect her human lover from a rival werewolf pack.
Well, a cool plot might be that the werewolf girlfriend is from a very traditional werewolf family. Her family doesn't approve of her relationship with a human. So she has to fight against her family's rules and expectations to stay with her human partner. Also, she could have special powers within her werewolf nature that she discovers while trying to protect her lover from various threats in the supernatural world.
One idea could be a Pokemon trainer who gets bitten by a werewolf-like Pokemon and starts to take on werewolf - like traits. They then have to struggle with controlling their new powers while still trying to compete in Pokemon battles.
One idea could be that the rented girlfriend and the client start to develop real feelings for each other during a trip they take together. Maybe they get stranded in a small town and have to rely on each other, which deepens their bond.
One plot idea could be that the vampire girlfriend is from a noble vampire family, and her family opposes her relationship with a human. So they have to fight against her family's wishes. Another idea is that the vampire girlfriend has lost her memory of being a vampire, and the human boyfriend has to help her discover her true nature while protecting her from other vampires who might take advantage of her.
One plot idea could be Ruby discovering she has werewolf abilities during a mission. She has to learn to control it while still fighting Grimm. Another could be that in a werewolf form, Ruby has enhanced senses that help her track down a powerful and elusive enemy. Or perhaps she forms a pack with some of her friends who also get werewolf-like powers and they have to protect Vale from a new werewolf - Grimm hybrid threat.
One idea could be a Young Justice member getting bitten and turning into a werewolf and having to hide it from the team at first. Another is a werewolf - based villain that the team has to face, who has some connection to an ancient werewolf legend in the DC universe. Maybe a story where a werewolf is used as a weapon by an evil organization against the Young Justice team.
Maybe there's a werewolf akuma. Hawkmoth takes advantage of an already existing werewolf in the city and akumatizes it. This werewolf - akuma has enhanced powers and is causing chaos. Ladybug and Chat Noir must figure out how to defeat it. They might need to discover the true identity of the werewolf to break the akuma's hold. It could be a person who was bitten recently and is struggling to control their new form.
One idea could be that Naruto and Hinata are part of a werewolf clan in a hidden village. They have to protect their clan from hunters who are after the werewolves' special powers. Naruto, with his usual determination, tries to find a way to make peace between the two groups while Hinata supports him and also uses her gentle yet strong skills to fend off any immediate threats.
Maybe there's a plot where a werewolf pack is causing trouble in the wizarding world and Hermione, Fleur, and some other characters team up to deal with it. Along the way, Hermione and Fleur develop a special bond that goes beyond friendship. There could be elements of mystery, action, and romance in such a plot.
One plot idea could be Ruby discovers she has werewolf abilities during a mission in a forest. She has to learn to control it while still fighting the Grimm. Another could be that there's a curse in Beacon Academy that turns Ruby into a werewolf, and her friends have to find a way to break the curse without hurting her.
A really interesting plot could be that a mad scientist creates a serum that turns Spider Man into a were - spider hybrid at the full moon. He has to struggle with this new form and the werewolf, who has experience with such transformations, helps him control it. This could lead to a lot of internal conflict for Spider Man as he tries to maintain his identity while dealing with these new instincts.