Lana's fanfiction is appealing because it allows fans to see her in different situations. Maybe she goes on a journey outside of Alola and has to adapt to new environments. This shows her versatility as a character.
Lana fanfiction often focuses on her unique personality traits. She's known for her calm and collected nature, especially when it comes to her water - related activities. In fanfiction, this can be exaggerated in a fun way. For example, she could be the only one who can calm a wild, angry Gyarados in a story. Fanfic writers can also explore her friendships with other characters from the Alola region.
One popular storyline could be Lana's journey during her pregnancy. Maybe she discovers she's pregnant while on a Pokemon adventure and has to balance taking care of herself and her unborn child with her Pokemon training. For example, she might have to take a break from some of the more dangerous battles or explorations. Another idea could be how her Pokemon react to her pregnancy. Some Pokemon might be very protective, like her water - type Pokemon creating a safe perimeter around her. And there could also be a story about Lana preparing for the arrival of her baby, such as making a special nursery with the help of her Pokemon friends, using their unique abilities to decorate or gather supplies.
Obviously Lana herself is the central character. Her Pokemon partners are very likely to be involved. For example, Popplio might be constantly by her side, providing emotional support. Ash and his Pikachu could also be part of the story. Ash, being a good friend, would probably offer his help and advice. Misty might also be there, sharing her own experiences or just being a good friend to Lana during this time. Brock could be involved too, perhaps using his knowledge of Pokemon and nature to ensure Lana has a healthy pregnancy. And other trainers from the Pokemon world who are friends with Lana might make appearances to show their support and be part of the story.
It varies. In certain comic arcs, Lana Lang may face life-threatening situations but doesn't necessarily die. The fate of her character can change based on the creative direction of the writers and the demands of the story.