I hope you guys do not get confused, but I have 2 versions of the reign of Scar, the first version only presents the theory that the only legitimate son of Scar was Nuka, Vitani and Kovu were adopted. The second version presents the theory that Scar had an heir before Nuka that was his legitimate son, the heir was Dhaibu. But this image is about the first version, that Dhaibu never existed.
It was a cold and gloomy afternoon, Scar would have to decide which of his three sons would be his heir. Nuka who was already a grown cub had hope to become the heir to be the oldest, Vitani, the middle child, despite showing to be strong and smart, would have no chance, Scar thought the females were nothing but weak servants, and then the youngest Kovu, Scar couldn't see anything special on cub, but Zira convinced Scar that Kovu would be the perfect heir, even that Scar always saw Nuka as the future king, but Zira was obsessed with Kovu, and would do anything for him to become king. In the end Scar chosed Kovu as his heir.
Kovu, Rafiki and Original image (C) Disney