The Hero's Ally

Possibly the Hero's best friend, closest ally, and one of Hero's largest problems. They might be another member of the Hero's race, a Flying Guide, Flying Non-Guide, Small Cute Animal, Small Cute Animal Plus, GREAT BALL OF LIGHT, Animated Inanimate, Robo Buddy, or what have you.

If they're too small or weak to fight alongside the Hero or provide some other kind of useful service (i.e be a guide), the Ally is more of a side than an ally. As a quick note, the difference between a side and an ally is that sides are usually there Just For Show and attracting a younger audience who like things such as Small Cute Animals while allies actually do something to help their friends.

The Hero's Ally might sometimes get tired of being the Hero's ally and betray them to join forced with the Villain. This decision might be made after the Hero goofs hard with their friend by having an argument with them, endangering their life, generally mistreating them, or forgetting they exist and leaving them in some God-forsaken hell zone. It can also be made after the Villain persuades the Hero's Ally into joining them by showing that the Hero isn't as great as they're made out to be or by promoting the greatness of working for evil.

The Hero's Ally Types
Nutshell: The sidekick-type friend who does their best to help out the Hero and the rest of their team.

Enhanced: The sidekick-type friend who rarely screws up, is loyal to their team, and always lends a hand in battle.

Cruel: The sidekick-type friend who eventually betrays their team.

Inverse: The Villain's Henchmen.

Atypical: No mirror.

Wrong: The sidekick-type friend who either messes around or up often