Fistful of Mercy from Fistful of Mercy on Vimeo.In this video, Fistful of Mercy performs in the studio and Joseph Arthur laughs along awkwardly with his bandmates.If your definition of supergroup is, “A group of musicians previously associated with other musical catalogs coming together to form a new one,” then the birth of a new supergroup will commence at 8 p.m. Thursday at Easy Street Records in West Seattle (4559 California Ave SW). The show is free. If you need reminding, here’s a quick refresher on the players involved:Ben Harper: You may remember him from your college days, particularly when he was fronting the dominant Innocent Criminals, a band that peaked with 1999’s Burn to Shine. Lately he’s been working with the less-satisfying Relentless7.Dhani Harrison: Yes, his dad was the cool Beatle.Joseph Arthur: Maybe you saw him at the Triple Door in January.