I drew this back in October, thought I'd upload it here.
Tama, Nala and Mheetu grew up together during scar's reign. Tama had always been a friend of Nala's, while Mheetu was her annoying younger brother she had to take with her everywhere. However, during the tough times of Scar's reign, they banded together, finding comfort in one another when it semed like the world was against them.
Scar became sort of wary of the three of them as they grew from cubs to teens. He knew they resented him, and he knew they were young and strong (especially fierce nala). He didn't like the lack of control he had over them, and would rid of them if he could have - but of course, they were strongly protected by the lionesses. So he had to make do with their existence.