Quest for Glory: So You Want to Be a Hero/Fridge

Fridge Logic

 * The bear in the caves is shackled in place and won't do serious harm unless you get very close to it. You can attack the bear and kill it, or you can avoid conflict by casting calm or feeding it before you walk past it to the caves, where the bear doesn't even care to notice you and can even be talked to. . So why is it that when you engage in combat with the bear, then cast calm while still in combat, would the bear calmly decide to eat you like every other monster or enemy you do this to? And why did it not occur to the hero to step back a bit once the bear is calmed, rather than stand there like a fresh slab of steak in front of a bear that, again, is trapped in place ? For that matter, why do enemies, such as the brigands, still calmly devour you if you also cast calm on them while in combat?