Thomas is obviously one of the main characters. His friends like Percy, James, and Gordon are also likely to be main characters as they are usually important in Thomas and Friends stories.
One main theme could be friendship. Thomas and his friends rely on each other, which shows the importance of friendship in their world. Another might be trust, as the title mentions 'trust Thomas'. They trust each other to do their jobs and help out on the railway.
Once upon a time, in a small town, there was a young man named Tim. He was a huge fan of Thomas Sanders Shorts. One day, after watching a particularly inspiring short, he decided to be more like the positive characters he saw. He started to spread kindness around the town. He helped the old lady cross the street, just like the helpful character in the short. People in the town were amazed by his change and soon, his kindness became contagious. The whole town was filled with love and harmony, all because of the inspiration from Thomas Sanders Shorts.
It could be members of the Akatsuki. Despite being antagonists in the original series, in the fanfiction they might have a change of heart. Maybe Pain, after seeing Naruto's resolve, decides to become his friend. Or it could be Orochimaru's former subordinates who see a different path through Naruto.
There are dark fanfictions that might take a more horror - inspired approach. For instance, the characters could be trapped in a haunted house or a cursed place. In this situation, they would have to face their deepest fears while also trying to find a way out. This type of fanfiction can be really intense as it plays on the fears of both the characters and the readers.
Friendship is another big theme. When different characters cross over, they form new friendships. For example, in a crossover with another popular series, the characters start off as strangers but end up relying on each other and becoming great friends through shared adventures.
One key element could be the characters. It might involve his friends or family members who play important roles during Christmas. Another element is likely the setting, perhaps a beautifully decorated Christmas - themed location.
Well, Thomas Sanders' Christmas story is likely to be full of his unique charm and humor. It might involve his experiences during Christmas, like how he celebrates with his friends or family, and perhaps some funny anecdotes that occur during the festive season.