Helen would have made a great military leader; in fact, she should maybe consider it as a career option.
She demands subservience and, in BB at least, she gets it. Why, do you think?
I think she set her stall out very early on by demonstrating to everyone in the house how she would behave with those who displeased her. She always did this, in the early days and weeks, with a maximum audience. She would then fortify the social delineations by making sure that those who pleased her got repeated instalments of propoganda against those who had displeased her. She would brook no disagreement and made this very clear - also from early on.
The housemates en masse had two choices, acquiesce or suffer social exclusion and, potentially, her wrath. The wrath could be reined in after a time because the social structure was solid. Also, the warnings from BB meant that she had to ease up. But the scaffolding was firmly in place.
Helen is very socially adept in a very negative way. There are many people like her in this world and I don't wish her ill - I just pity those who become enmeshed in her web.