In various Let's Plays, whenever the two are paired together they tend to go by their team name.
Both Michael and Gavin voice characters in RWBY and RWBY Chibi. Michael voices Sun Wukong, a Faunus stowaway who recurring secondary character since Volume 1. Sun ironically has a love affair with Blake Belladonna (voice of Arryn Zech) rather than Ruby Rose (voice of his wife Lindsay Jones). Gavin voices Scarlet David, a guest character who appears since Volume 3.
Both team members, as well as their larger 'Team Nice Kerry' teammate Kerry Shawcross, voice members of Team SSSN in RWBY. Michael is Sun (the team's namesake leader, much like his wife Lindsay with the R of the titular team), Gavin is Scarlet, and Kerry is Neptune.
Michael and Gavin have also collaborated very frequently in other Rooster Teeth projects outside of Achievement Hunter's projects (Play Pals, Lets Watch, Rage Quit, The Off Topic Podcast, Shenanigans, VS, GO! and AHWU). These include (but not limited to) Live action productions (Short comedy films, Sketch comedy skits, commercials, behind the scenes, murder-mystery, sci-if and more) such as Rooster Teeth Shorts, Immersion, Million Dollars, But... Lazer Team and Lazer Team 2, Ten Little Roosters, The Eleven Little Roosters, RT Life, RT Docs (Lets Play Live: The Documentary) in addition to animated cartoons such as RWBY, Red vs. Blue, and X-Ray and Vav, as well as podcasts such as The RT Podcast. This bromance them the nickname "Mavin".
Ryan Haywood was temporarily a member of Team Nice Dynamite during EXTREME, as he was playing on Michael's account. Like Michael. Ryan also voices a recurring secondary character in RWBY and RWBY Chibi: Beacon instructor Professor Peter Port.