In Greek mythology, Idyia (also Eidyia) was an Oceanid, daughter of Oceanus and Tethys, and queen of Aeetes of Colchis. By him she is mother of Medea and Chalciope; Absyrtus's maternity varies. Apollonius calls her the youngest of the Oceanides.
Adapted from Wikipedia, "Idyia" · CC BY-SA 4.0
I.Queen of Colchis
Hesiod lists Idyia among the Oceanids; the Theogony and later mythographers make her wife of Aeetes, son of Helios, and mother of Medea. Apollonius of Rhodes stresses that she is the youngest Oceanid and sets her in the Colchian palace when the Argonauts arrive.
Chalciope (mother of the sons who aid Jason) is regularly her daughter. Absyrtus is Medea's brother in many accounts, but only some sources make Idyia his mother as well — Apollodorus is among those who treat him as full sibling to Medea.
II.Name and role
Her name's link to seeing/knowing suits a river-ocean lineage tied to Medea's craft. She is not a major cult figure in Greece; her importance is genealogical and narrative — the Oceanid queen through whom the Colchian royal house and Medea's witchcraft enter the Argonaut saga.