The Cerberus Cheerleader.
As a character I find Miranda both annoying and deeply intriguing. Either ways she adds something very important to the Mass Effect world.
Miranda is one of two people on the Normandy to get their own cabin and desk comparable, if not larger than Shepard's desk space. This is clearly a reflection of her importance to the Illusive man and Cerberus. We aren't given much detail about the command structure of the Normandy other than Shepard is in charge, but Miranda does also make it clear that she answers to the TIM. So the privacy makes sense. While it is not stated stated it would also make sense that Miranda takes the role of second in command, with most of the crew answering to her and her to Shepard. Is is unclear how much of the crew is aware of Miranda's dual reporting.
Miranda is nearly always business. She is a terrible perfectionist and over worker. Her space reflects this, it is all business with multiple screens reflecting her need to be in control of everything. This desire to be control is further confirmed when she admits to wanting to put a control chip in Shepard.
Miranda is ruthless and unwavering loyal to Cerberus.
Well, that last sentence just isn't true. Miranda is ruthless to a point, but from the conversation she has with Shepard when questioned about Shepard's interactions with Cerberus from ME1, she explains how they where rouge factions. Interestingly she says that when Cerberus learned how smart the Rachni where they stopped the experiments. She disbelief that what happened to Jack was ordered by the TIM/ Cerberus shows that Miranda is ruthless, but to only to point.
This dovetails with the other part of the sentence. Miranda isn't loyal to Cerberus, but to an image of Cerberus that exists in her mind. Cerberus is just as bad as Jack says and Shepard has seen. Jack isn't the only child Cerberus has tried to turn into a weapon (see project overlord). In this light, Miranda sealing herself away from the crew of the Normandy makes sense. She sees everything, but only through that filter than allows her to keep that image of Cerberus intact.
This false image serves purpose. Miranda needs to be better than her father and if she was to accept to Cerberus for what it truly is, and she does in the end, she wouldn't be better than her father. TIM is aware of this and is aware that the most convincing lies are the ones we tell ourselves. I like to think that having to face Jack helped Miranda see the truth and helped her escape that closed off office.
