Scylla and Charyb are two Gizoids that are named after two sectors of the Twilight Cage. There is a main difference in what terrain they do best in. For Scylla, his terrain is underwater. And for Charyb his is land. Scylla is the sector that you meet the N'rrgal and Zoah in. When you first find Scylla, he will try to drown you. Before you fight Scylla Knuckles splits Sonic and him into two teams, Sonic and Tails fought Scylla and Knuckles and Shade fought Charyb. Scylla is the only one of these twin prefects that is fought twice. They both do not have the ability to copy abilities like normal Gizoids do.