Mary Davion was the oldest child of First Prince Roger Davion and Lois Chandler of Robinson, and as a part of her introduction to the art of governing Mary joined the Federated Suns Corps Diplomatique. Mary was subsequently stripped of her right to the throne by her father following a diplomatic mission to the Draconis Combine in 2696, a mission which saw her meet and fall in love with a young man named Soto Kurita. What would have been a relatively innocuous event became hugely contentious and would ultimately prompt a war because of those involved; not only was Mary Davion their heir to the throne of the Federated Suns, her husband was the youngest son of the Coordinator of the Draconis Combine, Urizen Kurita II, and brother to the future Coordinator Takiro Kurita. Both families protested against the marriage between Mary and Soto, but the two defied the protests and were married in 2698; following the marriage Mary returned to Luthien to live with Soto.
There was a precedent for other family lines taking the throne of the First Prince - the Davions had been willing to see the Holt-Davion family take power in the mid-twenty-seventh century - but that had been palatable because it kept House Davion in power. It was certain that any children Mary and Soto had would be raised as Kuritas, with little or no regard for their Davion heritage. In 2700 Roger passed the Act of Succession, barring Mary and her heirs from pressing a claim to the throne; Mary chose to accede to the act in 2702, giving up her rights for the man she loved. Neither Soto nor any other member of House Kurita signed the Act, however.
With the act in place Joseph Davion was recognised as Roger's heir, and the issue appeared to be resolved. The Kuritas made no effort to block or contest Joseph's succession in 2703, despite him being the youngest First Prince since Zane Davion. Mary and Soto had a son, Vincent, in 2699 and matters would remain peaceful until Mary's death in 2715. Takiro Kurita produced paperwork stating that while Mary had acceded to the Act of Succession, she hadn't abrogated the rights of her children, and that Vincent should be the legal heir to the throne of the Federated Suns. Takiro's claims were rejected by Joseph and ultimately led to the War of Davion Succession, one of the few open armed conflicts between member states during the era of the Star League and the death of Joseph Davion. The documents produced by Takiro disputing Joseph's claim weren't proved to be forgies until later.
- Historical: Liberation of Terra Volume 1, p. 16-18, "A Plague On Both Your Houses: The War of Davion Succession (Second Hidden War)"
- House Davion (The Federated Suns), p. 55, "Beginning of the End"
- Handbook: House Davion, p. 44, "Unholy Union"