Honeycomb-and-Birch's Links
Katz met Teufel on a trip to a small town [for supplies] back during the French v Prussian war. Teufel had been injured by a French priest and was in dire need of assistance, so Katz healed the black dog. Teufel and Adolphus however, do not get along.
Teufel will forever deny their injury however they are always greatful for Katz assistance.