Di Di is Di Jiu's twin sister. She was captured and had her eyes digged out by a doctor named Ge Yi.
However Liang Lu was the name of the one who was given the eyes and he also kept her alive for her blood as it could help him integrate them.
Liang Lu was from a 6-Star sect called "Abstruse Fire sect" which was obviously destroyed by Di Jiu after taking her back and healed her eyes.
She and Di Jiu are the last from their family.