A son of Ephraim Templeton and his senior wife Dinah, he was the half-brother of Princess Ruth of Manticore. He fled Masada with his father and other men of their family when the Star Kingdom of Manticore conquered and occupied the planet. They later formed the Church of Humanity Unchained (Defiant), an even more radical sect of the Church of Humanity Unchained.
In 1919 PD, Gideon led a Masadan mercenary force to the space station The Wages of Sin in order to kidnap Princess Ruth. They got hold of Berry Zilwicki, who posed as Ruth, but the kidnapping was spoiled; Gideon himself was killed by Lieutenant Ahmed Griggs of the Queen's Own. (CS1)