"Big brother Mheetu! Where are you going?" a young Nuka asked the older lion. "I'm going hunting. Wanna come with me?" Mheetu asked the younger lion. "My mother probably wouldn't let me", Nuka responded sadly. Mheetu knew that Zira was a very controlling lion, and with King Scar in control, that didn't make things any easier. However, Mheetu himself was a very rebellious lion. He wanted to set a good example for the younger lions in the Pridelands and show them that they shouldn't be afraid to challenge the rules and their leaders such as Scar and Zira. "All lions will eventually need to learn how to hunt. Don't worry, Nuka. We'll be back before Zira finds out!" Mheetu tells Nuka.
I imagine that Nuka looks up to Mheetu as an older brother figure, hence "Big brother Mheetu". Takes place during the reign of King Scar, some time before Simba returns.
I OWN NOTHING! LION KING BELONGS TO DISNEY!