To throw yourself in the path of an attack directed toward another character, make an attack roll. If this intercept roll hits an armor class as good as the attack roll being intercepted, the interceptor becomes the new target of the attack and moves between the attacker and the original target. The decision to intercept must be made prior to the attack roll.
Fighters may perform one intercept reaction per combat turn. Characters of other classes may only perform an intercept if they hold their action. Retainers directed to intercept attacks may be required to pass a morale check.
I want to add a sentence about how intercepts can only be attempted if they make sense logically, or are supported by the fiction (or whatever), but don’t have quite the proper language down yet.