Trigger 42

Trigger 42 is a green liquid, which was created by The Facility, in order to control X-23. X-23 was tortured into reacting to it via a combination of waterboarding and electric shock, so that whenever she smelled it she would instinctively attack whatever it was applied to, regardless of whether she wanted to or not.^[1] It was eventually determined by Jean Grey that Laura's consciousness retreated into one of her only happy memories of her time at the Facility as a defense mechanism in response to the torture, thus explaining her blackouts when under its effects.^[2]

Despite a conditioning process that made Laura uniquely susceptible to the scent while remaining innocuous to anyone else, somehow a variation was synthesized that would affect anyone who came in contact with it, and was tested in Paris by an unidentified woman who acquired a sample of the original trigger in Madripoor.^[3] It was later redesigned as a gas by Arcade on his Murderworld, to make X-23 attack her companions of the Avengers Academy^[4].

While Laura insisted she had no control over her actions while blacked out, she was eventually revealed to have some level of subconscious resistance. For example rather than killing anything in her path while under its effects, she was often able to refrain from a lethal response against individuals who were not marked with the trigger, engaging them only when they interfered with her efforts to attack the marked target. One such example was Kimura's attempt to use Laura to assassinate Tyger Tiger; although Laura successfully destroyed a Life-Model Decoy marked with the scent and placed by Tyger, Gambit, and Gabby as a distraction, she nonetheless spared the lives of the bodyguards who attempted to stop her.^[5]

Although Emma Frost speculated Laura would never be able to overcome her conditioning, and Laura herself believed the same, Jean was able to break it by telepathically observing her responses while under its effects, and helping her consciousness break free from the memory where it sheltered during her blackouts. Following Jean's efforts Laura is no longer affected by the trigger.^[2]