maintainer vs protagonist

maintainer and protagonist both are nouns.

Word	Noun	Adjective	Verb	Adverb
maintainer	Yes	No	No	No
protagonist	Yes	No	No	No

As nouns, protagonist is a hypernym of maintainer; that is, protagonist is a word with a broader meaning than maintainer:

Other hypernyms of maintainer include admirer, booster, champion, friend, supporter.

maintainer (noun)	protagonist (noun)
someone who upholds or maintains	a person who backs a politician or a team etc.
	the principal character in a work of fiction