One type of Tai Lung fanfic could be a 'what - if' scenario. What if Tai Lung had been redeemed? Writers could create a story where he overcomes his pride and anger, and uses his skills for good. This would change the whole dynamic of the story and give a new perspective on his character.
The OC should have a clear motivation that ties into Tai Lung's world. For example, if the OC is also a martial artist, they could be seeking to prove themselves against Tai Lung, which immediately creates a connection.
Tai Lung fanfic often gives readers a chance to see the character in a new light. It can show his softer side, which was not much explored in the original. Maybe he has a love interest that no one knew about, and a fanfic can build a whole story around that relationship.
A great plot twist might be that Po discovers he has some hidden connection to Tai Lung. For example, they could be related in some long - lost family way. This would add a whole new layer to their relationship and the story. Po would then have to grapple with the idea of fighting someone who is, in a way, family, and Tai Lung could use this knowledge to his advantage in different ways during their confrontations.
One key element is his early talent. He was very good at martial arts from the start. Another is his expectation of getting the Dragon Scroll. And also, his reaction to not getting it, which was turning bad.
Tai Lung was a snow leopard in the 'Kung Fu Panda' story. He was a very talented martial artist trained in the Jade Palace. He was once considered to be the Dragon Warrior in training. But his lust for power and his impatience led him to turn bad. He was promised the Dragon Scroll but when it was not given to him as he expected, he went on a rampage, which led to his exile.
In a fanfic, Tai Lung could be redeemed. Maybe he was wrongly influenced in the past. Po, being the kind - hearted panda, decides to help Tai Lung find his true self. They start training together, and Tai Lung begins to see the value in the Dragon Warrior's way of life. Their relationship evolves from enemies to something more like mentor - mentee in a reversed way, with Po guiding Tai Lung.
Often in fanfiction, Tai Lung's split between good and evil is a central theme. His upbringing in the kung fu temple might have instilled certain values that are considered 'good', like discipline and respect for the art. However, his jealousy towards Po and the sense of being wronged when he was denied the Dragon Scroll could be seen as the catalysts for his 'evil' transformation. Authors might explore how he could have been redeemed if he had been able to balance these two sides of his nature, or how his 'evil' side completely took over due to the circumstances.
Another storyline might involve a time - travel element. Tai Lung and Tigress are sent back in time to when Tai Lung was still a young student. Tigress, knowing what will happen in the future, tries to steer Tai Lung away from the path of jealousy and anger. They could form a bond as friends and training partners, and this new relationship changes the course of events, preventing Tai Lung's fall from grace.