Mike Stangle
- Played by: Adam Devine
- Jerk with a Heart of Gold: He may be petty and immature, but he does care for his family and genuinely feels bad about almost ruining the wedding.
- Red Oni, Blue Oni: The loud, impulsive red to Dave's more easygoing and mature blue.
- Toxic Friend Influence: It's repeatedly mentioned that Mike is holding Dave back.
Dave Stangle
- Played by: Zac Efron
- Big Little Brother: Despite being the younger brother he is easily able to kick Mike's ass.
- Nice Guy: Hard-partying tendencies aside, he is much nicer than Mike.
- Red Oni, Blue Oni: The mature and easygoing blue to Mike's loud, impulsive red.
Alice
- Played by: Anna Kendrick
- Broken Bird: Is going through a hard time having been dismissed by her fiancé at their wedding.
- Heterosexual Life-Partners: She and Tatiana have been best friends since they were kids.
- Nice Girl: Hard-partying tendencies aside, she is much nicer than Tatiana.
- Red Oni, Blue Oni: The nicer, meeker blue to Tatiana's red.
Tatiana
- Played by: Aubrey Plaza
- Heterosexual Life-Partners: She and Alice have been best friends since they were kids.
- Jerk with a Heart of Gold: She can be crass and manipulative, but she does it all to help her best friend.
- Red Oni, Blue Oni: The feisty and assertive red to Alice's blue.
