Sarabi and Zira (as a cub).
In my version Sarabi found her durring hunt and since she "lost" her only son, she decided to shelter Zira. Time passed and they became good friends. Sarabi became for Zira teacher, mentor, almost like a mother.... But then Zira grown up, fall in love in Scar and decided to become his queen. She become very agressive, fanatical
and it spoiled her friendship with Sarabi, broked her heart. Sadness and sorrow.

[sarcasm] Then Simba comes back from his exile and throwed Scar from the cliff... Happy end.