GRENADE TYPE(S): Frag (2 damage): A hit character in the target square is dealt 1 additional damage. Each other hit character is knocked back from the target square.

1) In what direction is a character knocked back if they started in the target square of the grenade? Or do they not move?

2) If the bolded portion of the above rule were not in the special rules, would the knockback originate from the character who threw the grenade?

Thanks in advance.

You needed to bold the other word and then it all makes sense.

1) it says each OTHER character is knocked back. If the attack would generate knock back in another way (doubles) it would be from the attacker.

2) If knock back is generated from the use of grenades that don't tell you how to treat knock back then it would be from the attacker.