One plot idea could be that the Ghost Phoenix is a guardian spirit of an ancient artifact in the Lost Girl universe. The main character discovers its existence and has to figure out how to communicate with it to unlock the secrets of the artifact.
Perhaps the Ghost Phoenix was once a powerful being that was wronged in the past. In the fanfic, it could be seeking revenge, and the Lost Girl characters get caught in the middle of its vendetta. They then have to decide whether to help the Ghost Phoenix or stop it, depending on their own moral compasses.
The Ghost Phoenix could be developed by giving it a unique personality. For example, it could be a very proud and noble being, with a sense of honor that guides its actions.
The plot might involve the brother's transformation into a Phoenix - like form in the fanfiction. This could be a result of some magical event or a hidden heritage. As a Phoenix, he would have to deal with the new responsibilities and powers. He could face challenges from other supernatural beings who either fear or envy his new form, all while trying to keep his sister safe and uphold the values of the Lost Girl world.
One possible plot could be that Max is a new girl in town. She accidentally stumbles upon the lair of the Lost Boys. At first, she's terrified, but as she gets to know them, she realizes they're not all bad. She could start to have a romantic interest in one of the boys, say David. And through her, the Lost Boys start to question their wild ways and consider a more 'human' lifestyle.
Perhaps a key idea in this fanfic is the mystery surrounding the lost primarchs. Their very existence being a secret could be used to create a sense of intrigue. The fanfic might explore how rumors and half - truths about them spread among different factions, and how these rumors influenced the actions and beliefs of various characters.
Well, perhaps the lost lover was sent to another dimension by some sort of magical or scientific accident. And the story could revolve around the main character finding a way to bring them back. Or, the lost lover could be a time - traveler and got stuck in a different era, and the plot is about the protagonist's journey to reunite with them across time.
A plot could revolve around Lauren getting into some trouble with a powerful Fae group, and Bo has to use all her powers and influence to rescue her. This would show Bo's loyalty to Lauren and how far she's willing to go for her. Also, during the rescue, they could have some deep emotional conversations that further develop their relationship.
A great plot could be that they marry in secret and then have to figure out how to announce it to their friends and families. There could be drama as some of their friends might not approve, like Bo's friends who worry about her getting too involved with the fae world through Dyson. Or perhaps they marry and then discover a hidden prophecy that their union is the key to saving the fae world from a great evil.
Well, it could be about a girl who initially has no interest in the Lost Boys. But then, maybe she stumbles upon one of their hangouts by accident. She could start to be intrigued by their carefree and somewhat dangerous lifestyle. As she gets to know more about them, she becomes a huge fan. She might start collecting things related to them, like posters or old photos from their adventures.
A third plot idea could be a crossover fanfic. Combine 'Lost Love in Times' with another popular fantasy world. For instance, if you cross it with a world of fairies, the main characters could be caught in a conflict between their own world and the fairy world, and their love could be tested in a whole new way. This would add new elements and challenges to their relationship.
One idea could be exploring a character's internal struggle during their time as an Animorph that wasn't fully covered in the original series. For example, they might be dealing with the moral implications of morphing into certain animals more than others.