Deuteragonist

A deuteragonist is the secondary main character in a drama, or media, who serves after the protagonist, the main character.

Deuteragonists in HMC media
More added later...
 * Sarah Mashmine/ Marshmallow Girl (Potato-Man's wife, partner and former love interest and who is a optimistic and bright anthropmorphic female marshmallow.)
 * Rico the Robin (Potato-Man's bestest buddy)
 * Nabil the Cat (The younger brother best friend of Osman the Dog)

Terms
Deuteragonists for example, are terms for the "secondary protagonist" or the "second main character". Deuteragonists also serve up to the main character also in a drama, serving as the character's best friend or assistant and the second important character up to date.

For example, Nabil the Cat is the best friend and adoptive younger brother of Osman the Dog, the titular protagonist of the series of the same name as served. Nabil is the deuteragonist of the series.

Also deuteragonists in secondary titles serve as the protagonist, replacing the original protagonist as the deuteragonist or tritagonist.

Female deuteragonists can serve as "female protagonists" a main protagonist who is a female.