III was left to be the ruler of Egypt with one of her sons.
She was favoring the younger son Ptolemy X Alexander I, so initially
she took him as a coregent. However under the pressure of the Alexandrians,
who preferred Lathyrus, she expelled Alexander to Cyprus to rule
it and took Lathyrus as he coregent.
Lathyrus married his sister Cleopatra IV and was forced by his mother
to divorce her and marry Cleopatra Selene his other sister. He was
then accused of plotting to kill his mother. The charge could be
set by his mother to force him out, as she always preferred Alexander.
And so Alexander I returned from Cyprus to co-rule Egypt with his
mother. A dispute erupted between them and Alexander I fled Alexandria
but after a conciliation he returned to Egypt.
Alexander I married his niece, daughter of Lathyrus, Berenice III.
He was cruel and was hated by the people. This stirred public resentment
and finally Alexandrians turned against him so he hastened away
from Egypt and was killed near Cyprus.
Once again Lathyrus assumed the throne after his brother's death
but he died in 82 BC, leaving a son called Ptolemy
XII Neos Dionysos.
Neos Dionysos was not a legitimate son so the only legitimate option
for the reign was Berenice III, Lathyrus' daughter.
Berenice III ruled Egypt for one year after which she was required
to marry, so she chose her stepson Ptolemy XI Alexander II, son
of Ptolemy X Alexander I.
Alexander II was much younger than Berenice III so he had her killed
right after the wedding. Since Berenice III had been very popular
among the people, an Alexandrian mob lynched Alexander II shortly
after his act.