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.
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.
Well, if Tai Lung was injured and Po found him instead of fighting him right away. Po could take Tai Lung to the Jade Palace and nurse him back to health. During this time, they would have conversations and Tai Lung would see the kindness in Po and the true meaning of the kung fu that he once coveted. This would change their relationship from one of enmity to one of mutual respect and a strange kind of friendship.
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.
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.
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.
One common theme could be the exploration of their relationship in a more romantic or complex way. Since they are from different sides in the Kung Fu Panda universe, there might be themes of redemption and understanding in the fanfiction.
One idea could be that Tai Lung meets an OC (original character) who has a unique fighting style that challenges his own. This could lead to a series of intense training sessions between them as Tai Lung is both intrigued and frustrated by this new opponent.