Cry out for Big Daddy's help, make him think you're a Little Sister. Watch as he fights to protect you.
Hypnotize Big Daddy is a Plasmid available in BioShock. When selected, it manifests itself as a pale green globule formed from Jack's palm, with visible deformities on his wrists and hands. Hypnotize Big Daddy is an active Plasmid that instantly releases a globule that homes in and bursts on the nearest Big Daddy within the player's central field of view at the cost of EVE. If this Plasmid is used on a Big Daddy that is guarding a Little Sister, the Little Sister will either retreat to a wall vent or will find a new Big Daddy.
Upon bursting, the target Big Daddy is splashed with a green liquid substance, immediately causing him to temporarily protect the player as he would a Little Sister. They will attack any enemies in the area that are hostile to the player. The light glowing from the face of the affected Big Daddy will turn green to indicate that he is friendly, and will flash when the Plasmid reaches the end of its effects. Directly or indirectly attacking a hypnotized Big Daddy will cause him to become hostile. A Big Daddy that is hostile to the player cannot be hypnotized.
Since one use of this Plasmid costs a considerable amount of EVE, a significant amount can be saved by casting other desired Plasmids first, and then casting Hypnotize Big Daddy to use the remaining EVE.
Big Daddies will get a new Little Sister after every time they are hypnotized. Use these opportunities to take multiple pictures using the Research Camera.
Plasmids and Tonics like Insect Swarm and Static Discharge should not be used in conjunction with Hypnotize Big Daddy, as the area of effect damage will cause a befriended Big Daddy to become hostile.
The Enrage Plasmid is a useful counterpart to Hypnotize Big Daddy, as it will allow for friendly and hostile Big Daddies to fight each other. The player can then dispatch the remaining one with less difficulty. One can also attack the required Big Daddy and back away, while the friendly one fights for the player.
It is possible to use this Plasmid to lure a Big Daddy into a Security Camera's field of view, and then cast Security Bullseye on them. Since the latter deals no damage, the Big Daddy will remain friendly, and will end up severely weakened or even dead after the alarm. This is only useful if the player solely wishes to loot the Big Daddy, as there will be no Little Sister as a reward.
EVE Saver will decrease the enormous cost in EVE when casting this Plasmid. However, unless Jack's EVE bar is significantly upgraded, even with the tonic equipped the entire bar will be invariably depleted.
Hypnotize Big Daddy returned to BioShock 2, under the new name of Hypnotize. It allows the player to "befriend" enemies temporarily, making them fight on one's side for the duration of the effect or until death.