Question: what is the difference between fill and don't fill in fortnite?
Answer: In Duos or Squads, “fill” just means that you will have random people in your team. However, “don't fill” is the opposite; it means that no one would be randomly paired up with you. If you want people to help you in Duos or Squads, but you set “Don't Fill”, invite some of your friends in the game.