Yes, there are quite a few. You can start by looking on fanfiction.net or Archive of Our Own. Just search for 'Tommen Baratheon OC' and you'll find a variety of stories. Some might focus on Tommen's relationships with original characters in different scenarios, like during his time as king or his interactions within the court.
There might be some out there. You could start by looking on fanfic platforms like Archive of Our Own. However, the availability and quality can vary. Some fanfics might focus on exploring different aspects of Tommen's character in a gay relationship context, while others could be more about creative reinterpretations of the world he's in with a gay relationship angle.
One common theme is friendship. Many stories feature an OC becoming friends with Tommen and guiding him through the difficult political situations in King's Landing. Another theme is love. There are fanfictions where an OC falls in love with Tommen, which can range from a sweet, innocent love to a more complex relationship. Power dynamics is also a theme, as Tommen is a king and the OC's position relative to his power is often explored.
One common theme could be self - discovery. Since Tommen is a character from a complex world, in gay fanfics, he might be on a journey to understand his own sexual orientation. Another theme could be forbidden love, considering the political and social structures in his fictional world. Also, some fanfics might explore how his relationships could change the power dynamics around him.
One great Stannis Baratheon marries OC fanfiction is 'The Queen by the Sea'. It beautifully weaves a story of how an original character fits into Stannis's world. The author does an excellent job of portraying Stannis's character as we know it from the original series, while also developing the OC in a believable way.
Some fanfictions might center around Tommen's marriage to Margaery. It could be a story where they actually work together to bring peace and prosperity to the Seven Kingdoms. They could form an alliance against the other power - hungry lords and ladies and make real changes in Westeros.
One great 'oc female Baratheon fanfiction' is 'The Baratheon Heiress'. It follows an original character who is a Baratheon daughter in a world full of political intrigue. Another is 'A Baratheon's Journey' which focuses on the oc's growth and her role in the family's legacy. There's also 'The Female Baratheon's Quest' where the character embarks on an adventure to prove herself in a male - dominated Westeros.
There might be a fanfiction where Tommen discovers a hidden power within himself. For example, he has the ability to communicate with animals. This new power helps him to better understand the needs of his people and make more informed decisions as king. He could use this power to gain the loyalty of his subjects in a unique way.
One great fanfiction could be about the Oc Son of Robert Baratheon trying to claim his rightful place in the Iron Throne. Maybe he has to face off against his siblings or other claimants. It could explore his character development as he discovers the truth about his father's actions and how it affects his own claim.
Well - developed characters. A good OC in a Baratheon - related fanfic should have a distinct personality, goals, and flaws. For example, if the OC is a Baratheon bastard, their struggle for acceptance in the family could be a great plot point.
You can try fanfic websites like Archive of Our Own (AO3). There are a lot of great works there. Just search for 'Baratheon' in the search bar and then filter through the results to find the ones with great original characters (OCs).