One common theme is friendship. Often, the OC forms a strong bond with Margaery, either helping her through difficult times or being helped by her. Another theme is political intrigue. Since Margaery is a major player in the political scene in the 'Game of Thrones' universe, the fanfictions usually involve the OC getting caught up in the plots and schemes.
Margaery can also be a symbol of hope or change in fanfictions with a male OC. If the male OC is disillusioned with the current state of Westeros, Margaery could represent a new way forward. Her charm and intelligence can inspire the male OC to support her in her plans to reform the kingdom. Their relationship then becomes a driving force for the plot, as they strive to make Westeros a better place while also dealing with their own personal feelings for each other.
There's also 'Margaery and the Newcomer'. In this fanfiction, the OC is a foreign noble who comes to Westeros. Margaery befriends the OC and together they navigate the dangerous waters of court politics. The story is interesting as it shows a different side of Margaery's character, her kindness and shrewdness at the same time.
In many 'Game of Thrones' fanfictions involving Margaery and a male OC, their relationship can be complex. It often depends on the writer's interpretation. Sometimes, they might be allies in the political intrigue of King's Landing. The male OC could be a knight who pledges loyalty to Margaery's family, and they develop a mutual respect that could potentially turn into a romantic relationship as the story unfolds.
There's also 'Margaery and the Mysterious OC'. This fanfic focuses on a mysterious original character who has some sort of premonition ability. Their interactions with Margaery are full of tension and mystery. It's a really engaging read as it weaves in elements of the unknown into the story. The plot twists keep you on your toes.
Characterization is key. The way the oc and Margaery are portrayed should be believable. For example, Margaery's charm and political acumen should be well - presented. Also, the relationship between them, whether it's friendship, rivalry or something else, needs to be well - developed.
One common theme is political intrigue. Given Margaery's role in the political world, a male OC often gets involved in the power plays and schemes alongside her. Another theme is love against all odds, as their different statuses or the complex political situation can create obstacles for their relationship.
A more light - hearted fanfiction could be that Tommen and Margaery are overjoyed about the pregnancy. They start planning for the baby's future right away. They host grand feasts to celebrate, and Margaery involves all the ladies of the court in preparing baby clothes and the nursery. Tommen dreams of teaching his son or daughter how to ride a horse and be a great ruler one day.
There's also 'Margaery's Unseen Ally', which is a fanfic that delves deep into the relationships Margaery has within the court. The oc in this story adds a new dimension to the existing relationships and power dynamics. It has some really well - written dialogue that brings the whole setting to life.
You can try fanfiction websites like Archive of Our Own (AO3). It has a vast collection of fanfics, and you can simply search for 'Male OC x Margaery Tyrell' in the search bar. Another option is FanFiction.net, though the quality may vary more there. Just be sure to read the tags and summaries to find the ones that suit your taste.