Jane is a sadistic guard of the Volturi and a pet of Aro's. She seems rather bitter and easily justifies inflicting pain on anyone with her power. Jane has a twin brother named Alec and they both reside in Volterra, Italy.

The Volturi had their eyes on Jane and Alec as potential people to change back when they were still human, but were waiting until they were older to change them. When frightened humans threatened to burn the twins at the stake, Aro was forced to change them while they were still young. Jane has since become one of the prize members of the Volturi Guard and is one of their highest ranking guards.

(Source: Jane at wikia.com)