|Out of universe information|
Otho was a Human and royal genealogist and Chamberlain on the Lord Protector's Planet in the Pegasus galaxy. One of his duties was to find the best match for the royal bloodline so that the royalty can still use the Ancient technology in the Tower City-ship.
When Otho came across Lt. Colonel John Sheppard in 2006, who possessed a stronger Ancient Technology Activation gene than any of the royals in several hundred years, he presented this to the Lord Protector, who wished to make him his son by arranging a marriage between Sheppard and his daughter Mara.
However, Otho had his own plans. He conspired with Tavius to murder the Lord Protector, likely by lacing his food with poisons. Tavius would ascend to the throne, and Otho would be given Mara in marriage.
However, when Sheppard presented all of the solutions to his concerns in the form of the Ancient Technology Activation gene therapy, Otho ended the previous agreement and took it himself, making him the most powerful wielder of the chair in centuries. Just as he took the throne, however, Dr. Rodney McKay initiated the tower's Stardrive, completely draining the Zero Point Module of all power, ending any possible future rule of the Lord Protectors.
After his plan was foiled Otho came at Sheppard with a knife, but Sheppard managed to steal it and cut him with it. Otho, who had laced the knife with poison, soon died of his own blade. (SGA: "The Tower")