Number Six is a Cylon variant capable of perfectly mimicking a human subject. Her semblance as a hot blonde in a red dress assists her infiltration skills for obvious reasons. Caprica Six gained access to the Colonial defense system, imparting to the Cylons computer information allowing the latter to neutralize that Colonial military and attack the Twelve Colonies. This same copy sacrificed herself to save Dr. Baltar. Memories of these events were assimilated and transferred into the downloaded copy Caprica-Six; the result was revered Cylon agent divided between loyalty to her own kind and occasional human attachments.