Does anyone else experience NPCs going absolutely mental whenever Dear are around? They'll suddenly become hyper aggressive, chasing them down to kill them, even if they're in the middle of a fire fight. Not only does this ruin any stealth approaches made but it's bloody annoying as well.

I don't think it's a bug. Radstags are often hostile even when unprovoked, and I think that the AI just regard them as enemies.

Yea not a bug. Radstags are always hostile when ur near them even if they run away and dont attack you.

It sort of makes sense in that they are food. People are supposedly starving... (although there's actually way too much food available for anyone in the game to actually be starving.)

You're not getting it. Not the Radstags, the NPCs. Companions, either temporary or permanent. The way they react, is with a level of aggression way above how they react to Gunners or Raiders or Ghouls etc. I've seen similar behaviour with Lydia in Skyrim who once chased a bandit half way across Skyrim before I finally had enough and used the console to turn her AI off. To repeat myself, this isn't the same behaviour they exhibit against other enemies, Radstags cause them to go bonkers. It's either a bug with their AI or a Bethesda troll.

ok fine, bug then I guess. All my followers attack and chase down radstags very aggressively... same as all other hostile enemies. So I guess its ur game.