Twilight has nothing to do with Harry Styles fanfics. It was created by Stephenie Meyer as an independent novel series with its own unique story and characters.
It could be trending because it features a new take on Harry Styles' personality or it offers a fantasy storyline that fans haven't seen before. Also, good promotion and word-of-mouth can contribute to its popularity.
Not really. Fanfic writers usually create stories that are more in line with the positive image of Harry Styles. They might write about meeting him backstage, going on a date with him, or being friends with him. A 'Kidnapped by Harry Styles fanfic' goes against the norm as it involves a rather negative and dangerous situation, so it's not a common type.
Lights are sometimes described as warm and inviting. For example, when Harry enters a room filled with warm, golden light, it gives a sense of comfort and safety. This can be used to show the character's feelings towards a place or a person. If it's a place associated with Harry, the warm light could represent the positive emotions the other characters have towards him.