While with the Mockers, Jack was senior lieutenant to the Nightmaster and was known for being given to violent tendencies and severe cruelty. The only reason he held this position was due to his ability of keeping the guild's bashers in line. Jimmy the Hand is the one who gave him the moniker "Laughing," although no one could remember him laughing at any time.
At Anita and Arutha's wedding, Jack was to assassinate Arutha using crossbow bolts dipped in Silverthorn poison. Jimmy was able to distract Jack from hitting Arutha however, the bolt struck Anita. After the attack, Jack was interrogated by Arutha's men and later died at the mercy of Lims-Kragma.