Quote Originally Posted by Tanarii View Post
Conversely, to be surprised a specific enemy individual must not be aware of, or become aware of via the check, any threat on the other side. A single specific threat on the other side they are aware of means they can't be surprised.

Note that the rules assume two sides. They don't tell us if three sides means you must be unaware and fail your checks vs all possible threats from all other sides, or not. I assume that's the rule but it's not specified.
Definitely up to the dungeon master, however if say a player were distracting a guard and another player walks up behind said guard and stabs him in the neck. I would allow the guard a perception roll to see if they know the other player is behind them. If they fail, surprise happens as normal because I would not say the distracting player is seen as a threat. If they succeed then obviously they turn around and say what are you doing and may get a few insight rolls based on circumstance.