Stories thrive on Conflict, and to have conflict, a story must have at least two combatants. Typically, although the moral distinctions between one combatant and the other can be as clear and simple or murky and vague as one likes, we in the audience will be inclined to take sides and wish for one combatant (the hero) to prevail over the other (the villain). If the hero wins, we'll usually consider this a Happy Ending, and if the villain wins, we'll usually see this as a Downer Ending. Needless to say, this is an Ending Tropes, so expect spoilers. Examples of Win Win Ending include: