One idea could be a story where Martha May discovers the Grinch's kind heart long before the events of the original story. Maybe she stumbles upon him secretly helping a lost Who in the forest and realizes there's more to him than his gruff exterior.
In many Martha May x Grinch fanfics, the theme of transformation is often present. The Grinch, who was once a bitter character, starts to change for the better because of Martha May. Also, the theme of acceptance - both Martha May accepting the Grinch as he is and vice versa - is quite common. These themes help to build an interesting and often heart - warming story.
You can start by having them interact in unexpected ways. For example, the Grinch could accidentally save Martha May from a small accident in the mountains near Whoville. This would create an initial bond of gratitude. Then, gradually build on their conversations, like the Grinch sharing his views on the Whos' noisy celebrations which Martha May initially dismisses but later starts to understand.
A prevalent theme could be the clash of personalities. The Grinch is, by nature, cynical and grouchy, while Martha might be more positive and kind - hearted. Fanfictions could focus on how they deal with these differences, whether they learn to accept each other as they are or if one of them changes to better fit the other. There might also be themes related to the power of love to overcome obstacles, like the Grinch's insecurities or Martha's family and friends not approving of their relationship at first.
One way to find good Martha May x Grinch fanfics is to follow some fanfic writers who are known for writing about Dr. Seuss - related characters. They might have written some interesting stories about Martha May and the Grinch. Also, some fanfic review blogs might have covered this pairing and can give you some leads on great reads.
One idea could be that Cindy Lou tries to teach the Grinch about the true meaning of Christmas in a more in - depth way than in the original story. For example, she takes him on a journey through the town to meet different people and hear their Christmas stories.
Perhaps they get involved in a community project. They could be working on a local garden restoration. Through this, they face various challenges like getting enough funds and dealing with difficult neighbors. This shared experience strengthens their bond in the fanfiction.
Well, another place could be Tumblr. There are often fanfic communities on Tumblr where people share or recommend fanfiction. You might need to use relevant tags like #Grinch #Martha #fanfiction to narrow down your search. Sometimes, the Tumblr search can be a bit tricky, but it's worth a shot.
Maybe a plot where Rose, who has her own experiences with the Doctor, and Martha, with her medical knowledge, find a strange alien illness spreading on Earth. They need to figure out its origin and how to stop it while also dealing with their feelings about the Doctor. For example, Rose might be a bit jealous of Martha's time with the Doctor, but they have to put that aside for the greater good.
One interesting idea could be May's return with a new and powerful Pokémon team. Maybe she has been on a secret training journey and comes back to surprise everyone in a big Pokémon battle tournament.
A Martha Speaks fanfiction might involve Martha becoming a detective. With her unique ability to talk, she can interview witnesses (both human and animal) and solve mysteries around the neighborhood, like finding out who stole the local bakery's special recipe.