Herod is described by Josephus as a competent person able to hunt, ride, shoot and win in combat. He was ruthless, ambitious, tyrannical and unhappy -- by the end of his life he had lost most of his family through his own actions.(1)
Herod was of Idumaean birth, his father, Antipater had a relationship with Antony, and had been in the service of Caesar. His father's relationship with Rome served Herod well as he secured Galilee and Jerusalem. Herod's rise to power began with his second marriage, which was to Mariamme. Mariamme was of the Hamunaean house, a long standing family line of High Priests (The King was also the High Priest). When Hyrcanus, Mariamme's grandfather, accepted Herod's request for Mariamme, he also gave Herod admittance as a member of the royal house.
When Herod's patron Cassius fell, Herod quickly gained Antony's favor. Under Antony's pressure Hyrcanus was forced to agree with the sons of Antipater becoming Tetrarchs -- Phasael (Herod's brother) and Herod.
Soon after becoming the Tetrarchs, the Parthians from Syria invaded. Herod escaped with his wife Doris, betrothed Mariamme, her mother Alexandra and his own mother, household, and all his troops. Mariamme's grandfather, Hyrcanus and Herod's brother, Phasael, were captured by the Parthians. Phasael committed suicide in his cell by breaking his skull against the wall. Hyrcanus' ears were cropped to prevent him from ever becoming High Priest again (he would no longer be physically without defect), and was exiled to Babylon. Though Herod seemed to genuinely grieve his brother's death, he was now free to dominate the family's potential to rule. When Herod learned of his brother's death he turned his attention to Rome, appealing to Antony for support. Herod contributed to the rebuilding of Rhodes, which had been damaged by the siege of Brutus and Cassius, to show his support of Rome. Upon having his interview with Antony and Octavian, Herod was presented as a champion of Rome, was given the title of King, and reinforced was sent to set sail and conquer his kingdom. Thus, Herod was appointed King in his own right without having to fall back on the legitimate royal line he obtained through Mariamme. This allowed Herod to rid himself of the members of the Hasmonaean family that he wished without eroding his validity to rule. By 37 BC, after much warfare, Herod had finally secured his kingdom.
Soon another threat came about in the form of Cleopatra's ambitions. Cleopatra having reestablished her dominance over Antony, began to utilize him to fulfill her dream of restoring the Ptolemiel Empire to its ancient limits; which included all of southern Syria leaving Herod in the way. When Cleopatra tried to persuade Antony to depose Herod he would not -- Antony had just installed Herod in a very rebel-prone area at great expense and trouble. To pacify her, Antony gave Cleopatra Jericho. Herod in turn leased Jericho from Cleopatra, even paying the part of the lease due from his neighbor, Malchus. With to ever present threat of Cleopatra appeased for the moment, Herod focused of the unrest in his kingdom.
Many Jews resented Herod, he was a sellout to the Romans, he was not a true Jew, and he was not of the Hasmonaean blood line. This concerned Herod because there were three surviving Hasmonaean males: Antigonus, Hyrcanus and Aristobulus. Antigonus was executed by Antony. Hyrcanus, who had been in exile in Babylon and received well by the large Jewish population there, was lured back home by Herod. Thinking it was safe to return, Hyrcanus did so, and after the death of Antony, Herod had Hyrcanus executed on trumped up charges of treason. Herod had always tried to avoid having a Hasmonaean in the High Priesthood, the High Priesthood was the traditional function of the King, it was a very public post and Herod was afraid the people would turn against him in support of a Hasmonaean High Priest. Under pressure of Cleopatra, Herod was forced to appoint Aristobulus, Mariamme's brother to the High Priesthood. Aristobulus was especially disturbing to Herod because he was popular with the people, handsome, young ( he was 16), and a Hasmonaean. After a failed attempt by Alexandra, Mariamme's mother, and Aristobulus to escape Herod with the help of Cleopatra, Herod had Aristoulus murdered by drowning.
When Antony falls, Herod presents himself to Octavian offering friendship, which Octavian accepts. After Antony's and Cleopatra's death the East is reorganized; Herod receives back the lands he was forced to give Cleopatra, and gains Gaza, Joppa, Strato's tower, Antedon. Samaria, Gadara and Hippos.(2) Herod died after 33 years of service to Rome, in about 4 BC (the time of CHRIST) Herod killed, disowned or exiled most of his family, always concerned he was being overthrown, and sometimes victim of his sister's, Salome's lies and plots.
(1)http://www.bible.org/docs/history/joe.htm
(2)The Herods of Judaea
(3)http://www.bible.org/docs/history/joe.htm