Scar had sat still above the gorge for nearly all day. Yesterday, he had seen a young cub's tail flick out of the water, and wondered where it came from. He had nearly fell asleep, but then he heard steps, and a thump, and had caught the scent of another lion.
"Mufasa? What are you doing? This better not be a joke!" Scar complained, only to hear no reply.
"Mufasa?" He asked, into the open.
Left without a reply, Scar decided that this was not Mufasa, but another rogue lion. He followed the scent, eventually finding its owner.
"A cub?" He asked, his shadow looming over the small and skinny cub.
--
This is my theory on how Scar and Zira had met. She was abused by her father, and one day, she decided to run away. She met with her brother, and they traversed the river. Nuka, her brother, drowns, but Zira is washed away to the Pride Lands, where she is later accepted into the pride.