To develop Sabertooth in fanfiction, you could start by delving deeper into his past traumas. His past might have made him the violent mutant he is, so exploring those events can add layers to his character. For example, if he had a difficult childhood, it could explain his aggression.
Well, in X - Men fanfiction, Sabertooth is often depicted as a complex character. His savage nature can be explored in different ways. Some fanfictions might focus on his backstory, like his origin and how he became the way he is. Others could explore his relationships with other X - Men characters, whether it's a rivalry or an unexpected alliance.
They could also be allies in some stories. If the OC has a similar view on the world as Sabertooth, perhaps a more survival - of - the - fittest mentality, they might team up. This could lead to some interesting plot developments as they face off against other mutants or even humans who oppose them.
A great plot could be a time - travel fanfic. Rogue and Sabertooth get sent back in time to an era when mutants were first emerging. They have to deal with the primitive understanding of mutants at that time and also try not to change the future too much. Or perhaps a story where Sabertooth is injured and Rogue has to use her powers to save him in a way that doesn't harm herself, leading to a new understanding between them.
As a rival. An OC with powers that can match or even outdo Sabertooth's would create intense battles and power struggles. This would keep the story exciting and full of action, constantly pitting their skills against each other.
In 'X Men Origins Story', Wolverine is the primary character. His complex personality and his search for his past are what drive the story forward. His brother Victor Creed, also known as Sabretooth, is an important character as well. He has a different view on their mutant abilities compared to Wolverine. Another main character is William Stryker. He is the mastermind behind many of the events in the movie, especially the Weapon X project which has a huge impact on Wolverine's life. There are also other mutants that make appearances, but these three are the most central to the plot.
The story mainly focuses on Wolverine's origin. It shows his early life, his relationship with his brother Victor Creed. Wolverine gets involved in various military operations and experiments. He endures a lot of pain and trauma during these experiences which ultimately lead to his transformation into the Wolverine we know, with his adamantium skeleton and retractable claws.
I think Beast would be a really interesting character to include. His intelligence and scientific knowledge could help in understanding any strange mutations or powers that come up in the story. And Wolverine, since he has his own history with Sabertooth. His presence could add tension and also a sense of brotherly - like rivalry that would enhance the overall story.