These are humanoid beings who passed on and went to Hades. They waited so long for their loved ones to join them there in the Underworld and when they didn't they felt lost and forgotten and so they traveled to the city of Lost Souls which is off the Sea of Lost Souls. These are also known as forgotten souls and are sometimes referred to the Sea of S7 forgetfulness. This allows them to forget the hurt and pain and all the time they spent waiting for their loved ones. Most of these beings just want to home so they can be loved and cherished and this helps save them they sometimes pass on sometimes they don't it just depends on you as an individual and then as an individual and what is wanted.