Slack was an old adventuring partner of Valkyrie. During their last quest, he brutally lost his arm and only barely survived. Following the event, Slack spent most of his time coping with his new situation, finding a new strength inside himself, that allowed him to compensate for his loss with an empowered fighting style focusing on his remaining arm.
Becoming popular with the younger acolytes due to his brashness and great sense of humor, Slack would often be found in the company of them, sharing his insight and guiding them in the struggles of youth.
When the party met Slack during the Briskwater crisis, he was protecting a group of five children against whatever dark force had taken over the monastery. Unlike Darceron, he had managed to steer clear of the black water corruption, but had awaited a status report from Darceron before moving the children to safety.