They're supposed to be an NPC, a "Non-Player Character." The term comes from video games, but in this meme format, it refers to a person who doesn't think for themselves, thoughtlessly repeating talking points, without engaging in good-faith discussion. Sort of like how a character in a video game just repeats predetermined lines of dialogue.

In this specific case, it's representing a particular sect of leftists, who criticize Liberals for being uncooperative with them (or will cooperate with people furthermore to their right, such as conservatives, reactionaries, or fascists, instead of with said leftists), who also won't vote for Joe Biden in the upcoming Presidential general election.

This is neither an endorsement nor rejection of the message, but they're saying (this sect of) leftists are hypocrites, thoughtlessly bashing Liberals instead of working together.

I hope that answered your question :-)

The kind of people who say "Liberals hate leftists more than fascists" and then proceed to oppose liberal coalition candidates in situations where a leftist coalition candidate is nonviable, even though fascism is the only realistic alternative outcome to the liberal coalition candidate winning.