Mara was fully aware of the fading Ancient Technology Activation gene in her family's bloodline, and made her physical body available to Lt. Colonel John Sheppard in the hopes that he may wed her and take her father's place, restoring the strength of the gene and ensuring the position of Lord Protector to her family.
Prior to his arrival, the chamberlain, Otho, and Tavius had conspired to poison and kill Tavius and Mara's father. When Tavius ascended to the throne, he would ensure Otho would be granted the right to wed Mara.
Mara pleaded with Sheppard to depart the tower, but Otho had already taken the Ancient Technology Activation gene therapy Sheppard had recently provided. Because of this, Otho would wed Mara and take the throne chair for himself. In a duel with Sheppard, Sheppard snatched Otho's knife and cut him with it. The knife, also laced with poison, killed Otho moments later, leaving Mara to wed who she wished.
With the tower drained of any power from the Zero Point Module when Dr. Rodney McKay briefly activated the City-ship's Stardrive, power was taken from the hands of the royal family and returned to Eldred's people below. (SGA: "The Tower")