She is a good friend of director
Kat Coiro, with whom she has worked on several projects. When Coiro brought her up during a meeting with Marvel executives and the showrunners of
She-Hulk : Avocate (2022), they were not familiar with her, but they agreed to invite her to audition for the role of Madisynn. They loved her performance so much that it made them cry with laughter, so much that they gave her the part on the spot. Madisynn quickly gained a cult-following in the Marvel fandom. However, as the episodes were already written before she was cast, her character only appeared in one episode. Writer and producer
Jessica Gao later admitted that if she had known earlier that Madisynn would become so popular, and that she would be played by Guggenheim, she would've definitely written her into more episodes.
