His suit was damaged and his genetic programming was screaming at him to go and get it fixed, but the Daddy just stood there. He stared down at the little shiny necklace in his hand, the fraying picture of a man, a woman, and a baby and he moaned. What was worse is that it looked so familiar, like he should know who they were, and this made him bellow louder and louder until he was driven into a fury. He pounded the vent his Little Sister had disappeared into, thrashed against the steel walls, slammed the massive drill he called a hand into the floor. Even working against the water each blow was terrifyingly powerful.
After a time the rage had passed. He put the golden chain into a pouch on his belt and headed for one of the many hidden stations Big Daddys used to repair and equip themselves. When Rapture was in it's infancy there was a plethora of men and women who would patch the suits of the divers responsible for the upkeep of the city, but as Andrew Ryan became more deluded he saw such people as simple and unworthy of being brought to his utopia. So it was set to the inventors and engineers of Rapture to devise a way to make these repairs automated and they did a brilliant job. The Big Daddy entered the bulkhead, waited for the room to be drained, moved into the next room and sat on the bench while his suit and helmet were attended to by a swarm of small robots.
When the repairs to his suit were complete his programming told him to pick up a rivet gun and go and look for areas to repair. That wasn't a diffcult at all, Rapture was dying. The soul of Rapture had died a long time ago but now it's body was going too. In four hours the Daddy found three repairs that required assisstance from another Daddy, and another three that never would have occurred if things were they before the fall.
None of this mattered to the Daddy though. Without his Little Sister he was just going through the motions, becoming nothing but a drone. Go here. Fix this.
Maybe that was the reason he didn't see the tentacle reaching from the darkness until it was to late for him to do anything about it.