EVE

From BioShock Wiki

EVE is a glowing bluish serum which allows the use of Plasmids, injected into the player's bloodstream using EVE Hypos. EVE can also be gained by absorbing the various consumables in Rapture. It is similar in function to "mana" in fantasy RPGs. EVE Hypos can be bought at most Circus of Values vending machines.

EVE is a modified version of ADAM, and while ADAM gives the ability to carry Plasmids in the body, EVE gives the power to use them. It was probably developed by Yi Suchong, in his study of plasmids and genetic modification. It is not certain why EVE is so common and ADAM scarce, although it is possible that large amounts of EVE can be produced using only a small quantity of ADAM.

The first design of the EVE Hypo (as seen in the "Bringing it Home" gameplay trailer), was a smaller, leaner needle full of a green murky liquid.

[edit] Trivia

• EVE and ADAM are a reference to the biblical characters Adam and Eve, who were granted immortality in the Garden of Eden until they fell from grace. This parallels the fall of Rapture and its citizens.