look at the vigilante class. It has an ability to use the grappled person to take hits for him.
Can the grappled individual be accidentally hit by an ally if the winner of the grapple's intent is to use the loser as a shield? If not is it just a +4 bonus to AC with no chance to hit the loser by his allies? So +4 to AC for both melee and ranged attacks with a ranged attacker suffering another -4 to hit for firing into melee unless he has point blank? I'm assuming a grapple is a constant struggle too with lot's of turning in place.
This actually started because the winner of the grapple has the option to move the grapple at half his movement. So during movement how do I handle attacks of opportunity?
Appreciate any advice, thanks!
It's important to note that unless you have a special ability I don't know about, when you establish a grapple, you move the target to an adjacent square. I don't know of a way using base rules to be in the same square as your opponent during a grapple.
Just to clarify, why are they in the same square? Normal grappling rules just specify they're adjacent. An adjacent creature could be used to provide cover, though attackers could always move around it. If you specifically wanna actively use a grappled creature as a shield against attacks, follow Chess Pwn's suggestion and check out vigilante's living shield talent.
For the movement, both the successful grappler's movement and the grapplee's movement because of the sustained grapple check would provoke. While most of the forced movement by maneuvers don't provoke without a Greater version of the maneuver feat allowing it, each maneuver had to specifically state such a case. The grapple-move action does not state such an exception.
"You can move both yourself and your target up to half your speed. At the end of your movement, you can place your target in any square adjacent to you. If you attempt to place your foe in a hazardous location, such as in a wall of fire or over a pit, the target receives a free attempt to break your grapple with a +4 bonus."
You get a choice to where he is adjacent to you at the END of your movement. While moving, I'd say he stays adjacent to you in the same relative position when the movement started. So get the rest of the party to position themselves or be prepared to do some zigzagging.