Herodias was Mariamne III’s sister, also a granddaughter of Mariamne I and Herod the King and was kin to all the other Mariamnes in Josephus. Her father had been executed by her grandfather. Her other grandmother was Salome sister of Herod. She was a veteran of the harem wars and the “abuse of the virgins” trial along with her sister. If she hadn’t been cleared of the charge of un-virginity, she could never have been betrothed to Herod son of Mariamne II, daughter of Simon the High Priest.
But then, suddenly, Herodias, perhaps even still below the age of puberty” was on the outside looking in. Her mother-in-law was divorced by Herod for plotting against him and was thrown out of court and Herodias and her young husband with her. Her husband’s prophecy made in the Temple by Simon the High Priest and his alliance/betrothal to a granddaughter of Mariamne the Hasmonean queen was not fulfilled. There was no re-betrothal for either of them. When next heard from in Josephus Herodias has a grown daughter—unfortunately not a son—and was living in a palace in Caesarea and was still the wife of the same by-passed Herod.
Josephus and the New Testament gospels give Herodias a speaking role. We know a lot about her for a woman of antiquity. It is Josephus who gives her daughter’s name as Salome…probably named for her grandmother Salome, Herod’s sister, while the gospels leave her unnamed. We know nothing of her life from her betrothal until both Josephus and the gospels start up again after the “lost” years when there was no king in Jerusalem hence no royal records for Josephus to draw on. But then Josephus devotes Book 18, Chapter 5 in Antiquities to her story:
About this time Aretas (king of Arabian Petrea) and Herod (Antipas) had a quarrel on the account following: Herod the tetrarch had married the daughter of Aretas, and had lived with her a great while; but when he was once (on his way to) Rome, he lodged with Herod, who was his brother indeed, but not by the same mother; for this Herod was the son of the high priest Simon’s daughter. However, he fell in love with Herodias, this last Herod’s wife, who was the daughter of Aristobulus their brother…This man ventured to talk to her about a marriage between them.
Let’s pause Josephus right there and look at what he has just said:
It is immediately clear what Herodias and Herod Antipas are up to…they were trying to preempt moves on the kingdom by Jesus and John, as reported by the gospels…AND present themselves to Rome as the king and queen alliance that could restore the Jewish kingdom as reported by Josephus. After Archelaus was deposed in 6 A.D., a Roman Procurator was put in place in Jerusalem. Like Herod Archelaus with a “Mariamne” as his wife, his brother Herod Antipas was making a play to have a Hasmonean Queen by his side…it had to mean something…and I doubt that “love” had anything to do with it…
…which address when (Herodias) admitted, an agreement was made for her to change her habitation, and come to him as soon as he should return from Rome; one article of this marriage also was this, that he should divorce Aretas’s daughter. So Antipas, when he had made this agreement, sailed to Rome…
Antipas the second son of Herod’s wife Malthace the Samaritan had been betrothed/allied with a troublesome Arabian neighbor, the usual role for younger princes not in the line of succession. (Another betrothal, like his brother Archelaus’ betrothal that fell through the cracks in the court record as Josephus does not mention it at the time.) With Antipas’ 20-odd years as the Tetrarch of Galilee and Perea for the Romans, he was a logical choice to be named king of a newly re-consolidated kingdom. His first move was to make an alliance with a granddaughter of Mariamne I the Hasmonean queen.
It is interesting that Herodias’ only proviso reported was that she be the ONLY wife of Antipas and therefore the uncontested Queen, exactly as her grandmother Mariamne I was Herod’s only official wife while she was alive (causing Herod to send his first wife Doris and son Antipater into exile). Hasmonean kings seem to have had only one wife, though they could have hundreds of concubines. Herod brought in the Arabian custom of having many wives…after he executed Mariamne the Queen.
Herodias may have had the bloodline and the ambition to make a run at the kingdom, but she was soon to come up against the old double standard, not with Rome but with her own right wing. Even Josephus was scandalized…
…but Herodias, their sister was married to Herod…the son of Herod the Great, who was born of Mariamne, the daughter of Simon the high priest, who had a daughter Salome; after whose birth, Herodias took upon her to confound the laws of our country, and divorce herself from her husband, while he was alive, and was married to Herod, [Antipas,] her husband’s brother by the father’s side… Antiquities of the Jews XVIII.V.4. 
In the next post, I will look a little closer at John the Baptist’s feud with Herodias over her remarriage as reported in the gospels, but for now we can consider that Jesus, as presented in the gospels, was stricter than the law on the issue of remarriage. He saw it as adultery.
What therefore God hath joined together, let not man put asunder…And I say unto you, Whosoever shall put away his wife, except it be for fornication, and shall marry another, committeth adultery; and whoso marrieth her which is put away doth commit adultery. Matthew 19:6-9
This episode represents the classic bind that royal women found themselves in…and what Jesus’ own mother had to deal with…as we will see. The women were raised to make marriage alliances for political reasons…but doing so made them “evil” to their own right wing…which included the followers of Jesus son of Mary.
 She wasn’t the first Herodian princess to divorce a husband, however. Her grandmother Salome divorced her second husband:
But some time afterward, when Salome…dissolved her marriage…though this was not according to the Jewish laws; for with us it is lawful for a husband to do so; but a wife if she departs from her husband, cannot of herself be married to another, unless her former husband put her away. However, Salome chose not to follow the law of her country, but the law of her authority, and so renounced her wedlock… Antiquities of the Jews XV.VII.10