- A mysterious proxy who invades Vincent's dreams. Her motives are unclear. It is, however, possible that it may be a form of Monad Proxy (subconsciously or consciously). Kazkis Proxy's conversation to Vincent in which he revealed that he and Monad were lovers as well as Ergo Proxy's depression and grief at seeing Monad Proxy in the tank seem to enforce Kazkis' words. Also, what she said to Vincent near the end episode of 20, telling him that she hated men that smelled of other women and vice versa, along with the irritated tone of voice reveal a form of jealousy. If the above is correct, however, it is hard explain exactly how Monad can access Vincent's conscience and subconscience. It is possible that some Proxies can affect other's subconscience much like Will B. Good did to Pino. Or what Senex seemed to have done to the woman in the prison cell (an adoring, worship-like trance, directed by Senex, seen in how she uses her actual name and what the Proxy represents).
- Another interpretation of Swan is that she is another attempt by Proxy One to destroy Vincent's love/dependance on Re-L (Re-L representing to Proxy One Vincent's desire to become human since Re-L is Monad made human) and force Vincent Law back into being Proxy One's agent of death, Ergo Proxy. Swan looks very much like a female version of Proxy One. Throughout the series, Proxy One has been manipulating events and people as well as tormenting Ergo Proxy/Vincent Law. Proxy One had a great hatred toward Monad since Monad took away his "instrument of death against the progenitors". It was insinuated that Ergo Proxy did not bear the same hatred toward the space-bound humans and did not want to follow Proxy One's mad desire to destroy the other Proxies and the domes to spite the returning humans. Monad, because she loved Ergo Proxy, took his memories at the expense of her own sanity. This made Ergo Proxy useless to Proxy One and in spiteful revenge Proxy One torments Vincent Law in many ways - Swan is one of them - forcing Vincent Law to slowly return to being Ergo.
Swan's office is copied from the interior of the Hill House, designed by Arts and Crafts era architect Charles Rennie Mackintosh