Big Daddy

"Huh? What's this?! A Big Daddy? Well, that stinks more than what do you think off... now they're just with the Little Sisters. Now I want to destroy that big one."

--Su Ji-Hoon, Unwelcome in Rapture

Big Daddies (originally named Protectors, and occasionally referred to as Mister Bubbles, or Mister B, by Little Sisters) are genetically enhanced human beings who have had their skin and organs grafted into an enormous diving suit, with Alpha Series being an apparent exception to the grafting process, though still heavily spliced. Their primary purpose is to protect Little Sisters while they escort them around Rapture. If all of the Little Sisters have been either harvested or saved in a level Big Daddies will wander to a vent like usual and bang on it. However, a Little Sister will not come out, causing the Big Daddy to groan in frustration and bang again before letting out a sad moan and walk away in an attempt to find another Little Sister.

Aside from the Alpha Series, Big Daddies communicate by uttering haunting sounds similar to that of whale calls. Alpha Series communicate with low, inhuman grunts and roars. For easier interpretation (as stated in the Deco Devolution art book), production model Big Daddies have a bioluminescent chemical substance which filled the helmet, displaying its state of emotion or mind. The Big Daddy has three different colors he will display.