Cid has a minor but important role in Final Fantasy VI. Here’s what the wiki says:
Cid Del Norte Marguez is a non-player character who invented Magitek technology for the Empire, a broad technological category that includes powered armor, weapons, and even pseudo-genetic engineering, all stemming from the extraction of magical essence from espers. He raised Celes as if she were his own daughter. Depending on the actions of the player, Cid either lives or dies.
My thoughts: The player being able to save Cid or let him die is pretty unique for a FF game of that era. Unlike Shadow, who can also be saved, keeping Cid alive has no material effect on the story or provide any bonus items to the player.
This Cid seems to be like a warm, friendly fella and cares deeply for Celes. He did work for an evil empire that brought about the end of the world, which some might consider unethical. But check out those mech