R. Dorothy Wayneright is the android assistant of Roger Smith in the series.
Introduced in Act:01 as Dorothy Soldano, daughter of rich scientist Miguel Soldano, she is later revealed to be an android constructed by him. Her actual "father" would be Timothy Wayneright, the man who commissioned her construction and father of the real and presumably deceased Dorothy Wayneright. To show her gratitude, and as a form of payment for Roger's help, she chose to move in with him and help his butler Norman Burg with his domestic work. However, as time passed, her responsibilities expanded to include aiding Norman with maintenance on Big O, and often accompanying Roger on negotiations and other assignments.
Dorothy stands just under 5 feet (60 inch, 150 cm) tall, has red hair and chalk-white skin. Despite being quite petite, she is extremely heavy; enough so that a large, grown man such as Dan Dastun was revealed on one occasion to have difficulty so much as budging her. Her forehead houses an illuminated CD ROM drive, which is loaded from a drawer made to resemble a hair ribbon. While capable of normal human facial expressions, in film noir tradition she typically maintains a pouty contour and a mildly sarcastic personality. She was at one point described by Angel, a friend of Roger's with whom she maintained a mildly antagonistic relationship, as being "perpetually foul-tempered". She was possessed of a dry and exceptionally blunt wit, often calling Roger a louse and on more than one occasion openly deriding other personality traits of his, such as his sense of fashion. With regard to Roger, she demonstrated throughout the series that she enjoys getting under his skin in inoffensive ways, such as loudly playing Roger's piano to rouse him when he sleeps past noon. She also demonstrated subtle hints of romantic feelings towards him. Offsetting her straightforward attitude is her general likability; she gets along rather well with virtually everyone, even those towards whom she harbors suspicion. From her conversation and behavior, it is evident that Dorothy has the capacity for human emotions. She has shown genuine fear on a number of occasions, and at one point revealed jealousy toward Angel's relationship with Roger and satisfaction from its failure to become romantic.
Dorothy is quite durable and much stronger than any human, able to punch down a brick wall with one blow or leap several dozen feet into the air. She has amazing balance, as seen during her moments of contemplation while standing precariously on the edge of Roger's balcony. She can run or bicycle at superhuman speed and does not require oxygen to operate. She possesses superhuman coordination, performing effortless gymnastic feats; at one point she even demonstrated the ability to steer a car with her foot while riding on its hood. That she takes regular meals with Roger indicates she can consume food and beverages, although she revealed in episode 11 "Daemonseed" that she does not possess a sense of taste. Dorothy also seems to have an unexplained connection to Big O itself. In Acts 20 and 21, when Dorothy is nearly destroyed by Alan Gabriel, Big O apparently sensed her plight and shut itself down in order to facilitate her rescue by Roger. In the final Act, she activated Big O's Final Stage weapon by plugging herself directly into the megadeus. She shows self-awareness and capacity for learning; throughout the series she exhibits talents at performance singing and virtuoso piano. It's suggested that the show's closing song is in fact R. Dorothy performing with a male vocalist, who may or may not be Roger.
Being of a mechanical nature, Dorothy is withdrawn, stoic, and cold. But she is not totally lacking in emotions. She is described as being "perpetually foul tempered" and at times can be extremely sarcastic, despite her insistence that she was programmed without the ability to feel emotions. While she tends to speak in a monotone whisper, there are times in which she has become visibly angry. Dorothy is also very insecure about her robotic nature: for instance, she refuses to board an elevator with a strict weight capacity due to the fact that it reminds her that she is merely a "copy" of the original Dorothy Wayneright.
Ironically, while she can pass as human under cursory inspection, Dorothy is the least "human" of any android seen throughout the series, as the rest are all shown to be capable of experiencing and expressing emotions. With the revelation that R. Dorothy possesses the original Dorothy Wayneright's mind, it is also implied that Dorothy's reticent behavior comes from the shock of her grandfather's death, which is indeed a very human reaction to have.
Dorothy complies with some of Isaac Asimov's 3 laws of robotics, but not all. For example, she is incapable of knowingly and willingly harming a human target, though if she is tricked into thinking that they are not human (whether by themselves or another), then she is capable of inflicting harm upon said target. Dorothy, while "obedient", also has a penchant for passive aggressiveness and deliberately acts inhuman to get a rise out of her master, whom she often refers to as a nuisance with her catchphrase, "You're a louse, Roger Smith".