Ptolemy I Sotor...The Savior....Usual linage is attributed to the man who raised him, Lagus, but in actaulity his mother, another Arsinoe, was the concubine of Philip II of Macedon. She was given to Lagus all ready pregnant. Who was Philip? The father of Alexander the Great. This means Ptolemy was Alexander's half brother. This means that the bloodline of Alexander coursed in the bloodline of the Ptolemies.
This secret went with her when she died. She never even told her brother the proper name of Set. A calculated move, for sure. Set was the heart of a warrior, force of raw power. Even a protector. But only to those who knew his name.
Intrigue and murder was the way of the day. Arsinoe felt, though all seemed fine between brother and sister, that anything could change at the snap of a finger. She died at age 44. Young for a Ptolemy. Usually the line was long lived. But there was health problems that plagued her as well as her brother....The later generations started to kill each other off because of of a madness born of inbreeding. that had not touched the first two generations. The downhill slide started with Ptolemy III. He was the son of the first wife of Ptolemy II, Arsinoe I, a daughter of a king of a foreign land. She was found plotting against her husband and was sent away disgraced. Later on to give his children by her a legitamacy in the Alexandrian bloodline, after his sister died, he postumously had them adopted by her. Odd but for a reason. But still the taint of their real mother's sins of betrayal stained the later generations.