How did Cleopatra overthrow her brother?

Cleopatra overthrew her brother, Ptolemy XIII, by strategically aligning herself with powerful Roman leaders, notably Julius Caesar. When Caesar arrived in Egypt, Cleopatra sought his support to regain control, presenting herself as a strong ruler rather than a mere sibling. With Caesar's military assistance, Cleopatra was able to defeat her brother's forces, ultimately leading to Ptolemy XIII's death and her consolidation of power as queen. This alliance with Rome significantly bolstered her position in the region.