Lena Oxton, also known as Tracer, is an Overwatch agent. She was handpicked to test a prototype of a teleporting fighter, the Slipstream. However, something went wrong during the test. The Slipstream's teleportation matrix malfunctioned, and it disappeared with Lena still in it. She was presumed dead. Fortunately, she reappeared a couple of months later, but she started to suffer from chronal disassociation. She was a living ghost, disappearing for hours and days at a time. Winston made a device capable of keeping her from disappearing and gave her the ability to control her own time.