One great Loid x Yor fanfic is 'A Spy's Heart'. It delves into the deeper emotions of Loid as he starts to truly care for Yor beyond their fake marriage setup. It shows his internal struggle between his mission and his growing feelings.
One great fanfic idea could be a story where Yor and Loid have to go on a mission together outside of their normal family cover. Maybe they end up in a foreign city and have to rely on each other more than ever. This would deepen their relationship and also add some exciting action and adventure elements to the story.