The Gate Children

The Gate Children are shadowy creatures living in the Gate who resemble small children. They live between the two gates of the parallel worlds, ours and the alchemical world. It is highly possible that they are humans before they are born or after they die,due to the fact that one of them becomes Wrath when Izumi gives her unborn baby's body to the Gate. Any time a human passes through the Gate, they become covered in the Gate Children, which makes them very strong and able to use powerful alchemy. This happens to Eckhart in The Conqueror of Shamballa. Despite the advantages of being covered in Gate Children, having too many on will cause a person to lose their mind. Going through the Gate twice (once each way) is usually enough to have too many Gate Children.

Trivia

 * The Gate Children appear only in the 2003 anime.
 * It is possible that the Gate Children are somehow connected to Truth.