Sentry was born eldest of her sister and brother. Ultima was their adoptive father as their parents had died during the attack of Radion. Ultima chose her and her siblings to be apart of his strike team, trying to transport the Radious to Earth and look for another appropriate home. She help in the fight to help protect the Terranians from the Exploricons, an ancient Radious civilization. After the Exploricons retreated, she was sent with Steele to get the other Radious on Earth. After she came back, and the Radious base was instated, Ultima soon died. As second-in-command, she was the only one ready to take control of Radious. After she was initiated the Great Radious War started. The Exploricons and the Decepticons joined forces to destroy and dominate the Radious. Half way through the war, the Decepticons went against the Exploricons and brain-washed them into joining them. Sentry lead the Radious to the winning of the two year long war, using the Dominance Sword which was crashed onto Terran. The Sword was destroyed to not be utilized for evil. Terranian was mostly at peace. Ultima died a long time afterward, a few years before passing the Radious onto her daughter.