Ana

Ana is the main antagonist of Rise of the Tomb Raider.

Lord Croft’s former lover, Ana is still friendly with Lara, but worries she’s headed down a self-destructive path.

It is eventually revealed that she is Konstantin's sister, and is working with him to recover the "Divine Source", an artifact which is purported to give it's holder eternal life. She is searching for the artifact due to the fact that she is dying of lung cancer (although she still smokes, telling Konstantin to "allow her her small pleasures").