Reid Campbell is a thoughtful neuroscience professor and Millie's best friend, characterized by his emotional intelligence and desire for genuine connection. His journey explores the challenge of moving from friendship to romance.

Chris Hill is a pragmatic and protective chemistry professor who acts as the responsible anchor of the friend group. He provides stability and offers grounded advice about the potential impacts of romance within their group.

Ed is a postdoctoral researcher known for his humor and awkward yet endearing disposition. As the group's guide in online dating, he offers comic relief and accidentally becomes involved in Millie's secret.

Alex Ramirez is a charming biochemistry professor with a cynical and superficial approach to dating. He values physical attraction over emotional connection and provides a contrasting viewpoint in the group, often adding comedic tension.