It's highly unlikely that the characters in 'House of the Dragon' would actually watch fanfiction about themselves. Fanfiction exists in our world, created by fans for fans, and the characters in the show are fictional entities within their own fictional universe. They don't have access to the fan - created stories about them.
One common misunderstanding is thinking that there are inappropriate or untrue stories like the so - called 'gay sex stories' associated with them. As mentioned before, the real focus of their stories was on their way of life, beliefs, and cultural elements.
There are some historical and fictional accounts that might suggest the existence of diverse relationships within the Ancient Celt Druid society. However, the evidence is often scarce and open to interpretation. Some scholars believe that their society was more accepting of different forms of relationships compared to some other contemporary cultures.
There is not much evidence of such explicit stories in mainstream Celtic mythology. Celtic mythology mainly focuses on heroes, gods, and their adventures. However, our understanding of Celtic society is still evolving, and new research may uncover different aspects in the future.
Most of what we know about the Ancient Celts comes from archaeological finds, some written accounts by the Romans and other sources. But these sources do not typically contain stories in the way you've described. The Celts had a complex society with various social and cultural norms, but their stories were more about battles, honor, and the supernatural rather than sexual relationships in this sense.
Definitely not a true story. House of the Dragon is a work of imagination and creativity. It weaves a complex tale of power, politics, and dragons within a fictional realm.
There is no evidence to suggest that there are such stories in legitimate Celtic folklore. Celtic history and Druid traditions mainly focus on religious beliefs, nature worship, and cultural practices rather than sexual themes in this regard.