Doctor Ernest Calderon (played by Gerard Plunkett) was an alien/human hybrid who worked at the Prangen pharmaceuticals company and provided special medical services to a San Diego nursing home. (TXF: "Christmas Carol", "Emily")
Calderon spent the 1990s tending to a group of elderly women, conducting experiments on them without their knowledge, including Anna Fugazzi. He administered hormonal drugs and put them to sleep in order to use them as surrogates for birthing other hybrids. The children would be put up for adoption. (TXF: "Emily")
One of the children, Emily Christine Sim, was adopted by Roberta and Marshall Sim. Calderon arranged for substantial monetary payments to keep Emily a patient of his under the guise of a double-blind drug study. He knew that Roberta, however, did not like the treatments and arranged for the payments to go directly to her to appease her. He nevertheless received paperwork from her to pull Emily from the study, only to have Marshall retract them. Calderon's colleagues then decided to kill Roberta and make it look like a suicide. (TXF: "Christmas Carol", "Emily")
Calderon soon met Dana Scully and John Kresge who investigated the death, and gave them his cover story. He also denied a request for Emily's medical records when requested, saying she must stay in the study and accusing Scully of endangering the girl's health. He then got a visit from Fox Mulder who threatened him, pulling a gun on him and demanding that he do more to save Emily's life. Scared, he left for the nursing home. There, Calderon met with a two men from the hybrid police who killed him and took his appearance to confuse Mulder. (TXF: "Christmas Carol", "Emily")
A while later, still in the guise of Calderon, one of the hybrids incapacitated Detective John Kresge via exposure to his toxic blood but allowed Mulder to escape by posing as Kresge. When the pseudo-Kresge fled in Calderon's car, Mulder realized the deception. (TXF: "Emily")
A man identical to Doctor Calderon is seen arresting Jeremiah Smith at the Social Security Administration office in Washington, D.C. in 1996 (TXF: "Talitha Cumi"). This seems to imply that Calderon was part of a clone series doing various tasks for the Syndicate.
Background Information[]
Despite being part of the hybridization work, the alien playing Doctor Calderon appeared not to be entirely trusted by the other aliens, since he was killed presumably because he was losing control of the situation. (TXF: "Emily")