Carrow's full name is Illumined Brother Carrow Belmerrick.
In JQS1, Carrow starts as a Cleric of Vieris gifted with healing magic. He uses this healing magic on Perf after Perf is beaten by Glorion, but quickly into the season, Carrow is shot by three orc bowmen at Rilk's order. He dies. Nara orders Perf to heal Carrow, but Perf's retromancy turns him undead instead.
As a sentient corporeal (revenant), Carrow assists Perf and Nara as they battle the orcish warparty. They are soon captured by the Assassin.
In JQS2, the Assassin takes Carrow and the others through Sumber, the City of the Dead. Carrow tries to turn undead using his holy symbol, but he looks at it and accidentally turns himself. After running, he comes face to face with the Pale Lady, Death. Carrow denounces her and calls upon Vieris, but his arm explodes.
He again calls upon Vieris to deliver them from the assassin. Vieris sends an angel who turns on Carrow and destroys his holy symbol. Strong like Bull labels Carrow a death priest and asks him to imbue a horn with shadow to defeat the angel's protective aura. To save Perf, Carrow does. He and the others are recaptured by the assassin, but Carrow chews off his own arms (one being the angel's) to free himself.
In JQS3, (Incomplete)
Another description can be found on the Dead Gentleman Wiki's character page.