Psychiatric physician based at Willoughby State Hospital. Likely a fabricated mouthpiece used by the Asuran Niam, rather than a real person, Dr. Fletcher was responsible for directing Dr. Elizabeth Weir's psychiatric treatment at the hospital. Compassionate and patient, he made himself available to her at many hours of the day.
Fletcher explained to Elizabeth that she had been checked into the hospital after she collapsed in mid-sentence at the negotiating table, mediating a treaty concerning nuclear proliferation in North Africa. In reality Weir never left Atlantis. Niam's nanites fabricated a convincing reality within her mind where Weir's mental state reacted directly to whether or not she would take her medication. If she didn't, she would witness nightmarish visages.
Dr. Fletcher, an agent of Niam inside Elizabeth's mind, would punish Weir with imprisonment if she refused to take her pills. This was a direct correlation with the spread of nanites in the real world. If Weir yielded to the medication, the spread of the nanites increased.
Weir eventually defeated Dr. Fletcher, who revealed himself as Niam, by refusing to give into the physician's wishes. Finding herself at Stargate Command, she passed through the event horizon in her mind and regained consciousness in the real world.
The Real World - Niam, eager to spread his nanites, uses the mask of the compassionate Dr. Adam Fletcher to encourage a positive response to Dr. Weir's medication.