Cymnea

[Taewakan]

Being the first wife, Cymnea was of an age with Oberon (back in the day.) Her children were prodigies in the art of Warfare and had their own agendas (including or especially Cymnea.)
Oberon didn't like this. He thought Cymnea was the most dangerous of the lot so he exiled her to a shadow that her children could not get into (at the time) thanks to his control over shadow, complements of the Pattern.
Then he had Osric and Finndo killed off (in theory.)
Benedict was smarter than his elder brothers. He lived. Thus the Game of Thrones is played.
To this day Benedict has no designs on the throne
...Or does he?
I cannot imagine Cymnea taking the deaths of her boys well.
We know Dworkin was a Lord of Chaos and I imagine he thought Cymnea was a good match for Oberon for a number of reason. He may even have arranged the marriage.
Thus we have a hint at her level of power - then.

Scroll ahead a couple millennia and we may find that Benedict and his mother have been reunited by a cabal of other wives and children for the express purpose of, as many an ex-wife has said, making HIM pay.
can you imagine if (just) Clarissa and her brood were to join forces with Cymnea and hers (no one ever said that Cymnea was not pregnant when Oberon put her in exile...)
What if we have yet to see the incarnation of Mordred (Cymnea's 4th child (or 7th)) in the Amber series?

Ah! The joys of a demonic imagination.

[RPGPundit]

Yes, the "angry ex-wives club" does seem like a good plot concept.

[Taewakan]

Yeah, there is even a movie you can take hints from