here's how i have fit this quest into MY story
Rattus was hired by someone to keep us busy and try to get us to hurt ourselves, by destroying our reputation. robbing the bank in arnika, will get the Higardi to turn on us (or so the tiny little Ratt brains think!), and possibly help us garner more enemies than friends.
but as it's only a little Rattkin plot, it's a completely lame one! and of course, Rattus heads for his boltholt so that we won't come after him for payback later on.
ta-da! works for me! LOL.
V***V