Since I'm not familiar with this specific fanfic, it's hard to say for sure. But generally in fanfics, themes like love, relationships, and family could be common.
One common theme is redemption. Many fanfics explore Vicky's character and give her a chance to redeem herself in Timmy's eyes. For example, she might start to show kindness towards him after some event.
One popular 'Timmy Turner x Vicky fanfic' could be 'The Unlikely Bond'. It explores an interesting dynamic between them where they start to understand each other in a different way than in the original show.
One possible plot could be that Timmy, through some magical mix - up, ends up in a situation where he has to marry Vicky. At first, he's horrified, but as the story progresses, he discovers a different side of Vicky. Maybe she has some insecurities that she's been hiding behind her mean exterior. And through Timmy's kindness, she starts to change for the better, and they end up having a somewhat unconventional but loving relationship.
One challenge could be their different personalities. Timmy is a kind - hearted boy, while Vicky is often mean. They would need to find a way to balance each other out. For example, Timmy might have to teach Vicky how to be more empathetic, and Vicky would need to stop being so controlling.
Unfortunately, without more context about what 'timmy vicky married lemon' really refers to in the fanfic world, it's hard to point out specific stories. However, when looking for fanfics, you can use detailed search terms and filters on fanfic platforms to narrow down your search.
Well, I don't actually know the specific story of Vicky and Tim. It could be a story about their friendship, where they might have met at school. They could have shared hobbies like reading or playing sports together.