"Many of these stragglers were former miners driven to psychological breakdown by the pressures of long hours, horrible working conditions, and long-term exposure to raw kato residue, which had been demonstrated to have a corrosive effect on unprotected flesh even in particulate
form, leading to respiratory ailments, skin rashes, and even blindness.
Though the term 'straggler' was originally aimed at those who had remained in
Avernus, it eventually grew to encompass anyone displaying these characteristics."
--Shogo website
Stragglers are Kato miners affected from exposure to the element and thus have a damaged mental state and deranged personalities.
