Not Ana, Elise. Ana became a Guardian, her sister Elise did not. She was not forged in the Traveler's Light like us. She was a member of FWC. Her father, Clovis Bray II, owned the research company Clovis Bray, named for his father Clovis Bray I, on Mars. They had a department specializing in Exo production. She rushed to Mars to put her mind into an Exo so she could use Maya Sundaresh's Machine and see the future. She survived using the machine without going insane thanks to her Exo body. She then created a prototype ship, the Eon Trespass, which basically connects her with time travel by its name. The FWC then created a ship based on her design, called the Teilhard War. This reflects their view of her, and their beliefs of an evolving timeline. The visions she saw led her to Osiris and his study of Vex Timegates. She became his assistant, and eventually went through a Gate. She was able to control the Vex energy and uses it to travel forward in time to the next cycle. Keep in mind that Destiny is set in a repeating timeline of Light ages and Dark ages. They are mostly identical to each other every time they occur. This is best seen in the opening cinematic on Mars where the mountains are changing shape while the astronauts walk. This is a flip-book-like animation of different ages having the same event. Destiny draws heavily from Bungie's past games, like Myth, and from the Souls games. That is where this idea comes from. The Machine allowed Elise to see a Guardian who would break the cycle, and allow Light to prevail eternally. She always meets and evaluates our Guardian to see if she has found the right age. We manage to defeat the Dark Heart that is corrupting the Vex; who are not the architects of a dark future, but of all of timeless creation. They only attack those who endanger the structure. They became corrupted when Crota opened a hole in-between the Vex transport network and Oryx's Throne World. When Crota emerged on Luna, he brought the Vex to the Sol System with him. As a thank you for ending her search, she gives you her rifle. Then comes Atheon's plan to manipulate all realities to align with the Hezen Vex, which is oddly similar to Heathen Vex. They are the outliers of the Vex. They are atheists of the Vex cause. They seek to conquer instead of build. After we defeat Atheon and his brood, she sees that we have done what she did not even expect. She rewards us with another version of her rifle, from a different time. It, however, becomes lost in time. Lakshmi-2, remembers Elise, and helps us retrieve the weapon. Along the way we find a time lost artifact, Ana Bray's bracelet. It was carried by Elise after Ana died at Twilight Gap. She lost it there after grieving for Ana in our age, and we found it; giving us a connection to her and to her weapon. We were then able to defeat the Vex Gate Lord standing in-between us and No Time to Explain. She etched a word into it, "Soon," meaning that she wishes to meet us and finally explain herself and her goals. This will either occur in the next expansion, Vex Void; or in Destiny 2: The Shattered Suns. Destiny 2 is supposed to involve Osiris, so his assistant could be important. Only [i]Time[/i] will tell, Guardians. TL;DR: Elise Bray is the Exo Stranger.