Vivian Darkbloom

Vivian Darkbloom is the alter ego of Alison DiLaurentis. After Caleb begins hacking "A's" phone, the girl's discover that Alison had created an alter ego, after she too was being victimized by "A." The name "Vivian" comes from latin, and it means "Alive" Very few people know Vivian's true identy, some of those few are Duncan Albert, the four liars, and possibly Mona.

Creation Theories
Various theories have arisen from the revelation of Vivian's identity:
 * One is that Ali pretended to be a separate character, Vivian, in order to be able to sneak around and do certain things with her "boyfriend" Ian Thomas.
 * Another is that Ali wanted to become someone else in order to sneak around without "A" knowing, under their radar.
 * Maybe Ali made this separate identity, in order to throw "A" off, in order to find out "A's" identity.
 * Many fans speculate, that Vivian is somehow actually Courtney but there is little evidence to support this claim.
 * Ali may have wanted to go off to Brookhaven and meet with Duncan Albert (a friend who flew her from Hilton Head the day she died)
 * That Courtney actually died the night of September 1, 2009 like she did in the books and Ali created the persona beforehand and is using it to spy on the liars and maybe the leader of "The "A-Team" who visited Mona in Radley Sanitarium.
 * Or that Ali was close to figuring out who A was, and she was using Vivian to learn more without A knowig she was there.