It would be very complex. Initially, Uther would be in shock. He has been hunting magic - users, and now his son is one. But he might also feel a sense of protectiveness. Merlin, on the other hand, would be confused and angry at being lied to about his identity. Eventually, they might start to understand each other more. Uther could see the good in Merlin's magic and Merlin could see the reasons behind Uther's actions, even if he doesn't agree with them all.
Uther might initially be shocked. He has always been so against magic, so he could be furious at first. He might feel betrayed by Merlin, whom he has known for a while.
One common theme is identity crisis. Merlin has to come to terms with being the son of a man who has persecuted his kind (magic users). Another theme is family secrets. The fact that this truth has been hidden for so long creates a lot of drama.
I'm not sure of a specific title, but in general, fanfictions with this premise often explore the idea of Merlin having to hide his identity as Uther's son. They usually rewrite parts of the original story to incorporate this new relationship. For example, Merlin might struggle with feelings of betrayal towards Uther, who has been so harsh on magic users, not knowing that his own son is one. This can lead to a whole new set of character dynamics and plot twists within the Camelot - centric story.
One great Merlin Uther fanfiction is 'The King's Regret'. It delves into the complex relationship between Merlin and Uther. It shows how Uther might have reacted differently to Merlin's magic if he had known the truth earlier. Another is 'Uther's Hidden Affection', which explores a more emotional side of Uther towards Merlin, a side that was perhaps masked by his hatred for magic in the original series.
One possible plot could be Merlin growing up in hiding, not knowing his true identity. Then, as he gets closer to Camelot, strange things start to happen. Magic stirs in him more powerfully, and he begins to have visions related to Uther. Eventually, through a series of adventures and near - misses, the truth is revealed. Maybe Merlin saves Uther's life in a crucial moment, and Uther starts to suspect there's more to Merlin than meets the eye.
There probably is. The Merlin fandom is quite large and diverse. Some fans might be interested in exploring the consequences and emotional turmoil that would result from such a dark event as Uther killing Merlin. You can look for it on popular fanfiction websites like Archive of Our Own or FanFiction.net.
One great Merlin and Uther fanfic could be one that explores their complex relationship before Uther's death. It might focus on how Merlin, despite Uther's harsh actions at times, still respected the king as the leader of Camelot. Another could be a fanfic where Uther discovers Merlin's magic early on and has to deal with his own prejudices in a different way. There are also fanfics that place them in alternate universes, like a modern - day setting where they have to adapt to new rules and social norms while still maintaining their core characteristics.
One great aspect of Uther Pendragon and Merlin fanfiction is the exploration of their complex relationship. In the original series, Uther is often at odds with Merlin's magic, but in fanfiction, authors can reimagine their dynamic. For example, some stories might have Uther discover Merlin's magic earlier and instead of persecuting him, learn to accept it due to Merlin's selfless use of magic for the good of Camelot.