Gapers will attempt to walk towards Isaac by taking the most direct route possible. If there is no way to reach Isaac, due to obstacles such as Rocks or Poop blocking the way, they will stand still and avoid moving towards Isaac until a proper route is created.
In Hard Mode, the eternal Gapers acts the same as the original version, but they move a bit faster and always turns into Eternal Horf or Eternal Gusher upon death.
- The Gaper, Mulligan, Hive, and Swarmer are all the same monster in stages of decay and infestation. The Gaper seems to be the fresh corpses, before decay sets in.