|Full name:||Dr. Susan Duncan|
|Manner of Death:||Poisoned by P.T. Westmoreland and Virginia Coady|
|Marital status:||Widow of Ethan Duncan|
|Significant Other/s:|| Ethan Duncan (husband) †|
Ira (lover) †
|Family:|| Ethan Duncan (husband) † |
Rachel Duncan (adoptive daughter; subject)
Ira (secret adoptive son) †
|Portrayed by:|| Rosemary Dunsmore|
Christy Bruce (Young)
|Season/s:||3, 4, 5|
|First appearance:||"History Yet to Be Written"|
|Latest appearance:||"Manacled Slim Wrists"|
Ethan and Susan Duncan were prominent scientists involved in Project Leda—the project that created the female clones of the series. Despite her husband Ethan being a genius, he claims Susan was actually the smarter of the two and that she had solved something called the protein spindle problem which was critical in the success of creating the clones.
Susan and Ethan originally hired an African woman named Amelia as a surrogate mother with the intent that they would raise the child. Susan and Ethan had impregnated her with a cloned embryo from Project Leda. Amelia, sensing something sinister about the project, fled during her pregnancy and later gave birth to identical twins Sarah and Helena.
The Duncans later came to raise another one of the clones: Rachel. The Duncans never lied to Rachel about her being a clone and she grew up knowing about her origins. The Neolutionists in the Dyad Institute later took Rachel from the Duncans to groom her to be one of their leaders.
Susan and several other Project Leda scientists supposedly died in a laboratory fire that also destroyed the notes and the genome on the original batch the female clones were derived from. Ethan Duncan claims Aldous Leekie set the fire. It took Dyad 20 years and 400 failed attempts before they were able to create another clone (Charlotte Bowles) but it is implied that even this was not a complete success as one of Charlotte's legs is malformed.
Years after the fire, she is revealed to be alive and healthy, residing at a Neolutionist stronghold in an unknown location. It is her intent to have her daughter, Rachel, raise the new clone Charlotte.
|Season 3 appearances|
|The Weight of This Combination||Transitory Sacrifices of Crisis||Formalized, Complex, and Costly||Newer Elements of Our Defense||Scarred by Many Past Frustrations|
|Certain Agony of the Battlefield||Community of Dreadful Fear and Hate||Ruthless in Purpose, and Insidious in Method||Insolvent Phantom of Tomorrow||History Yet to Be Written|
|Season 4 appearances|
|The Collapse of Nature||Transgressive Border Crossing||The Stigmata of Progress||From Indistinct to Rational Control||Human Raw Material|
|The Scandal of Altruism||The Antisocialism of Sex||The Redesign of Natural Objects||The Mitigation of Competition||From Dancing Mice to Psychopaths|
|Season 5 appearances|
|The Few Who Dare||Clutch of Greed||Beneath Her Heart||Let the Children and Childbearers Toil||Ease For Idle Millionaires|
|Manacled Slim Wrists||Gag or Throttle||Guillotines Decide||One Fettered Slave||To Right the Wrongs of Many|