Samira has a strong split between her public and private sides. She is very dishonest about who she really is. In public she's very prim and proper, or at least tries to be. She stays restrained and tries to avoid any displays of strong emotion, either positive or negative, and typically seeks to avoid resorting to insults even against those she dislikes. Occasionally she makes a poor comment here and there, but she tries not to. Basically, Samira's been trained during her life as a slave to be completely subservient. She believes she's actually offending people if she presents her "real self", because she expects that no one cares about her and her issues and would dismiss her for opening up. Therefore, in public, she continues to present herself as a servant to endear herself to others and to protect her from their wrath.
Beneath the mask is an entirely different story, though. She's a complete wreck under it. She bottles up all of her emotions and feelings in public, and so is desperate for any kind of release. Hence the drugs, pornography, massive material collection (making up for never owning anything), and plushies (physical connection is something she desires a lot because her social restraint means she has almost no one to be close to. Thus cuddling with stuffed animals as a replacement). Very, very few people see her beneath the mask, since she keeps it on even in private situations unless she is very familiar with the person she's with. I think only Aldrith and Pieter have interacted with her "real self", and even then it's been mostly accidental and only came out when they pressured her. Seriphyn also managed to bother her enough for her to slap him.
Samira is written to simultaneously be someone both slavery supporters and slavery detractors can point to and say is a perfect example of why their argument is right. In public, she's perfectly conditioned, very polite, religious, and selfless. In private, she's been pretty messed up by the experience.