Monika is noted by the other characters to be smart, beautiful, confident and athletic. She's not as talkative as the other girls, but this implied to not be through choice. 

Monika had previously been a part of the Debate Club but left due to all the inner politics and drama, highlighting a desire for order, freedom of topic and friendliness. 

The Literature Club, which she founded after leaving the Debate Club, is very important to Monika. She aspires for it to be a place to showcase and grow everyone's passion for literature. Monika openly displays care and concern for her club mates, praising each member's writing style and even comparing them to famous authors and poets. 

Starting from Act 2, she shows a much more manipulative personality. It is revealed that Monika was self-aware all along and resented from being made into a minor role. She becomes infatuated with the player and urges them to spend more time with her. Monika begins trying to dispose of her club mates so the player is forced to choose her, after her attempts to make the other girls unlikable fail. Her desire and ambition lead her to become obsessive in this goal, highlighted by the fact that all of her poems are about the player.