Erin is a sound engineer who had a short romantic relationship with Gunnar Scott.
Gunnar meets her when she is working as a soundboard engineer on tour and they embark on a relationship, which causes friction with Scarlett. While performing at a small venue, Scarlett signals to her to increase the sound but Erin accidentally blows the soundboard causing the power to fail, which leads to the concert becoming an acoustic gig.
In spite of Gunnar giving out to Erin about this, they continue to see each other, even nosily having sex in the adjoining room to Scarlett's. However, the latter eventually realizes that she still has feelings for him and he realizes he feels the same, which leads to him ending his relationship with Erin.