Dr. Enrique Castillo was a scientist who belonged to the Scientific Advisory Council of the United Earth Ministries. He supported the idea that humans should welcome the alien Cyrollans and join the Symbiotry of Peaceful Beings.
In 2310, during the Conference on Alien Interchange in the World Science Center, Castillo gave an inspired speech which overshadowed the arguments of Dr. Elliot Sinclair who objected to the Symbiotry, and persuaded the fellow scientists to trust the aliens.
- Sometime later Sinclair sent the android Mercury back in time to assassinate Castillo, but this attempt was averted by Gage Blackwood.
In the process Castillo became the first Earth ambassador to the Symbiotry and welcomed the alien delegates on Caldoria.