I'm not sure if there's a particularly 'good' one. Lemon fanfics often contain inappropriate or adult - themed content. It's better to focus on fanfics that explore the relationship between Spiderman and Gwen Stacy in a more positive and story - driven way, like those that might deal with their adventures together or the emotional aspects of their connection.
Gwen could have a huge impact on Peter's story. She could give him emotional support, which Peter often lacks. In Spiderman 3, Peter goes through a lot, and Gwen could be the stable presence he needs.
Often, Aunt May can be a really well - written character in these fanfictions. She might be the one who gives Peter some sage advice about his relationship with Gwen. Or she could accidentally discover Peter's secret identity and have to deal with the shock and worry in a very human way. Her motherly love and concern for Peter add an extra layer of depth to the stories.
One interesting scenario could be Peter and Gwen going on a double - date with their superhero friends. They get to show a different side of their lives outside of the web - slinging and science stuff.
Perhaps there's a power - stealing device in the fanfiction. It's stolen by a villain and used on the Avengers, but Gwen is immune. So the Avengers, now with reduced powers, end up fighting Gwen who is trying to get the device back. Or it could be that Gwen discovers a threat to her world that the Avengers don't believe in, and they try to stop her from taking action, leading to a conflict.
A good one often has well - developed characters. It should capture the essence of both Spiderman and Gwen Stacy as we know them from the comics or movies. For example, Spiderman's sense of responsibility and Gwen's intelligence and independence.
In a Spider Gwen and Spiderman kiss fanfiction, it could be a moment of great passion. Maybe it's a moment of celebration after they've defeated a powerful villain together. Their kiss could symbolize the deep connection they've developed through their shared experiences as superheroes.