Felix and Oswald interact in a rather complex way. They often start off on the wrong foot. Felix might be more cautious and reserved, while Oswald could be more impulsive. For instance, Oswald might rush into a situation in the ink - filled corridors, and Felix would be hesitant, causing some tension between them.
Often, their interactions are full of tension. Since the Volturi and the Cullens have a complex relationship, Felix and Bella are on opposite sides at first. However, in some stories, Bella's kindness towards Felix, despite his fearsome reputation, can start to change his perception of her. He may start to see her as an individual rather than just a part of the Cullen clan, leading to more positive interactions.
Felix is killed by the creatures or the situation related to the unseen threats in the 'Bird Box' novel. Lucy also meets her end due to the same overall danger that plagues the world in the story.
Often, their interaction is full of unspoken words. Felix may have a hidden agenda, while Adrien is just trying to be friendly. They could end up in a sort of power struggle, each trying to assert their own identity. But as the story progresses, they could start to respect each other more and find common ground.
It could be a story of two people meeting by chance at a winery and falling in love. Fotos could capture their first glance, romantic walks among the vines, and toasting with wine.
Max Schreiber is quite interesting. He's a wizard with his own motives and powers that often play into the adventures of Gotrek and Felix. His magical abilities add an extra layer of complexity to the story.
I'm not sure specifically what 'felix fanfic' is about without more context. It could be a fanfic related to a character named Felix. Maybe it's about Felix's adventures, relationships, or his role in a particular fictional world.