
Fortnite's ongoing story currently involves a plot where the game's characters could use the help of some additional heroes. The world could always use more of them, I've heard.
And that's how four Overwatch characters have been introduced into the world of Fortnite as part of its current season's Act Three events. OW heroes Tracer, D.Va, Mercy, and Genji will be joining the ever-growing ranks of cosmetic skins tomorrow.