Many people think that Vitani and Kovu are litter mates.
Others say Vitani is Scar's daughter.
Both of these remarks are false.
Few understand what really happened.
Which is why we are going back to the beginning of this story...
Zira was never a true Pridelander. She just came across the Pridelands during Scar's reign. The Pridelands at this time were an unforgiving wasteland, but Zira, and those with her, saw someone at Pride Rock and decided to visit anyway. Scar had welcomed them, and Zira quickly became a devoted follower. But she brought it to an extreme.
Scar took advantage of Zira's devotion, and they had a son. However, the son was weak and generally useless. This cub was Nuka. With the firstborn being a failure, Scar and Zira decided they would not have a proper heir together.
At this point, Zira began to wander in the Farlands, and eventually found a rouge lion, with whom she had a seconde cub. She left with the cub in the night. This seconde born cub seemed quite perfect, until they discovered that it was a female. Her name was Vitani. Now Scar still had no heir, and Zira really wanted to help, but she couldn't. She couldn't have a son with Scar because... Nuka. And Vitani's father was long gone. There was only one choice. She had to get a son somewhere else. From someone else.
After some time, Zira located a couple who had recently had a cub. The father was Ujasari, and the mother was Furaha. Their cub was named Bahati. One look at Bahati told Zira he was exactly what she needed. So she snuck up on the family and attacked Furaha from behind. While Ujasari tended to her, Zira a volé, étole the cub and was gone. To cover their tracks, Scar and Zira renamed the cub Kovu.
So now toi know who Vitani's parents are, along with getting some insight into the stories of Zira, Nuka, and Kovu. If toi have any plus questions on these subjects, let me know in the comments.