Absyrtus

[15] As a descendant of Helios, Apsyrtus grew into a radiant young man and lived in his own palace, next to the loftiest building where his father, the queen and his other sisters dwelt.

This can be explained by the fact that Apsyrtus was born to a Caucasian nymph, Asterodeia, to Aeetes before he made Eidyia, the youngest daughter of Tethys and Oceanus, his wedded wife.

Later on, a civil war in Colchis occurred because the brother of Aeëtes, Perses, came with a Scythian army to the country in order to unseat the king out off his throne.

[18] Aeetes was aided by the Argonauts because he vowed to give the Golden Fleece to Jason in return of the favor for the incoming fight.

[23] Apollonius of Rhodes presents a variation on this tradition in Argonautica (Book 4): Jason murdered Medea's brother on one of the "Brygean Islands" (an island sacred to the goddess Artemis and located in the modern Kvarner Gulf), where he was lured by Medea with false promises – their first (and last) meeting after leaving Colchis.