Page "Lucius Tarquinius Superbus" Paragraph 4

According to Livy, the younger of the two daughters of Servius Tullius was of fiercer temperament than her sister, yet she originally married Aruns, who had a milder disposition than his elder brother.

The younger Tullia came to despise Aruns and developed a plot with Tarquin.

Together, they arranged the murder of their respective siblings, in quick succession, and were thereafter married to each other.