Bellatrix inherited the classic beauty that the House of Black is known to possess. At the age of 31, her pale skin is free from lines and blemishes. However, her eyes are droopy and she usually has a tired appearance regardless of whether or not she was up all night torturing Mudbloods. Her hair is black, thick, and is meticulously groomed both to please her parents and because wizards are so easily fooled by a pretty face. Her eyes are a dark brown, nearly black.
In a word - fanatic. Bellatrix belongs strongly in her cause, and even more so in her Master. Lucius may be the right hand man but Bellatrix is his most devoted. She is always ready to take on a challenge. She's proactive and willing to succeed at any costs. She is not a good leader because most of her followers would end up incapacitated if they dared question her orders. She is not a good follower for this reason either. Bellatrix works best alone or in the company of those she feels to be equally devout.
As the eldest of the three sisters, Bellatrix grew up knowing the importance of making her family proud. She didn't want to go into the princess mould that Narcissa was being poured into and she knew better than to bring shame on the family by going Andromeda's route. Because there were no sons on her side of the Black family, Bellatrix assumed the most masculine role in the family. In addition to the doting she'd received from her family, she learned from an early age how to be cute to get what she wanted. After spending a few years as a member of Slytherin house, Bellatrix found it was far more effective to hurt and threaten to achieve her goals. Her voracious appetite for the dark arts was rivalled only by her contemporary, Severus Snape. After leaving school, she became more entranced with their family friend. Not one to be content with sitting around at home and supervising the house elves' baking, she did her best to be sure Voldemort was aware of her. Bellatrix recently joined the Knights of Walpurgis and works tirelessly to prove herself worthy.