Marcy also easily forgives her friends whenever they make a mistake as she would mostly see the good side of their intentions over the bad. In addition, Marcy tries her best to make her friends happy, as shown in " A Day at the Aquarium," when she encouraged Anne to go with the Plantars instead of staying with her in Newtopia.
Also, Marcy cares about her other friends as she would do anything to help them just like she would for Anne and Sasha. However, upon reuniting with Anne and Sasha at different times, Marcy was happy to see them again and was relived that they were okay, which shows that she was concerned about them. Marcy cares about Anne and Sasha greatly as she missed them when they were separated in Amphibia. Also, when King Andrias revealed his true nature once he's been given the Calamity Box, Marcy was horrified to discover she had been used by a genocidal maniac. After Sasha revealed that she played her and Anne just to put Grime's invasion plan into motion, Marcy was not only shocked of her betrayal but also refused to side with her because of her actions and now sees how controlling she can be. A trait that allows people like her friend Sasha, Captain Grime, Mayor Toadstool, and King Andrias to use her to their advantage. Despite her intelligence, Marcy is also a very naive person. While people like Rosemary, Lavender and Ginger would view her as a weirdo because of her quirky personality, this would lead to her becoming friends with Maddie Flour, as well as training as Maddie's apprentice in the magical arts. Even things such as seeds, history, and other things girls her age normally wouldn't be interested in will cause her to talk nonstop.
Marcy is also a highly energetic and bubbly person, and gets easily excited about anything that interests her. She loves video games, research and puzzles. Despite this, both she and Anne are still often affected by Sasha's influence. Ever since she came to Amphibia, however, she has learned to take care of herself better, and make her own decisions without many people's influence. Back on earth, Marcy was somewhat dependent on her friends, as she constantly relied on Anne to look out for her, and was used to having Sasha make decisions for her. Also, Marcy is very clumsy, but she generally remains forgetful and unbothered by it. Marcy has shown to be a peace maker as she tried to smooth out arguments between her friends, especially Anne and Sasha. In addition, Marcy is a good listener as she listens to her friends about their problems as she offers them advice or comfort for whatever is bothering them.
She is curious and takes interest in culture, being the one who discovered the Calamity Box. Marcy is an intelligent young female, and is often seen researching things and taking notes. Unaware that he is secretly plotting a mysterious agenda involving her and her friends. Upon arrival in Amphibia and being found by the inhabitants of Newtopia, Marcy serves Andrias as his close aide and chief ranger of the Newtopian Knight Guard. She learned of a mysterious chest located in some store that she, Anne, and Sasha stole it from and was alongside them when Anne opens it which sends her, Sasha, and herself to Amphibia. Marcy is close friends Anne and Sasha and serves as the brains of the trio, is an expert gamer, and has many clumsy moments which that Anne and Sasha have to counter.