PANPC (Pack Attack NPC Edition) is a unique scripted AI management system for Fallout 4. Rather than treating each enemy as an individual proximity-based reaction agent (basically, a mine with a gun), this system generates social feedback between NPCs belonging to the same or allied factions.

Enemies factor the overhaul health and success of their “team” into their tactical decisions, adjusting their strategies based on their social and threat awareness. As a result, they will switch between ranged, melee, defensive, and offensive tactics based on their perceptions of team advantage and individual risk.

PANPC is basically an NPC behavior and combat director for Fallout 4, similar in concept to the Director system in Left 4 Dead. This mod exploits the Bethesda AI system in order to create more complex, difficult, and varied combat situations that dynamically adapt to the player’s gameplay.

PANPC makes major changes to how supported NPC groups fight. Rather than simply rushing you in the open as a group, these NPCs will break and cover, retreat and flank, run and hide, and even lie in wait. They're more likely to ambush, less likely to engage in suicidal charges, and more certain to switch to hand-to-hand combat if you get too close and they like their odds. In short, PANPC completely overhauls and upgrades the combat AI for all supported NPC groups.

A Biggles Essential
I can't imagine a run without PANPC!

In Biggles Own Words
Both of Greslin's AI mods, PANPC and PACE, compliment eachother as you don't want dumb companions with smart NPCs or vica versa, so you should think about using both.