Soo for the longest time I always thought that Zira looked like a Sarabi/Scar crack baby. Sarabi and Zira almost have the exact same colours, and Scar and Zira share a lot of features. Throw in a few genes passed down from some grandparents, and it sorta makes sense.... well, in my mind anyway xD
I dunno. All it takes is a neglectful father that Scar has the potential to be (all Zira would want is her Dad's approval) and poor Sarabi being cast by the way-side in favour of such a father. I dunno, in my mind it could have happened during Scars reign. Zira also would be only slightly younger than Simba too.
Just something I think could be plausible. I dunno. What do you guys think?