Billie Lurk has played a prominent role throughout the mythos of Dishonored: She was present at the assassination of Empress Jessamine Kaldwin, aided Daud throughout the Knife of Dunwall expansion, and even gets some work in Dishonored 2. For that game's expansion, the upcoming Death of the Outsider, she finally becomes the star, and so fittingly Bethesda has put out a new teaser revealing more about who she is and what she brings to the table.
Spoilers ahead—Billie could quite easily end up dead at the end of Knife of Dunwall, but in the Dishonored canon she slips away to start a new, presumably quieter life. Obviously that doesn't go quite as planned, and she ends up rejoining her mentor-turned-adversary Daud for one last job.
"When we find her in Death of the Outsider she's sort of getting it back together. She's finding purpose in her life again, and she's taking action," Arkane creative director Harvey Smith says in the video. "She's going to change things for the better."
In Death of the Outsider, Billie wields powers and gadgets that haven't previously been seen, including the Sliver of the Eye, a sort of supernatural monocle that presumably gives her special visual abilities. (It may also be a cool callback to a malevolent gem in Thief: The Dark Project called The Eye, although that's strictly speculation on my part.) Her arm is made of chunks of the Void—I'm sure that's an interesting story all by itself—and she packs a "Voltaic Gun," a sort of electrified wrist-bow.
Dishonored 2: Death of the Outsider comes out on September 15.