Who is Tequila from The Diamond Age, or, Young Lady's Illustrated Primer and what is their importance?

Tequila is the mostly absent mother of Nell and Harv. She is technically Bud's girlfriend, but upon the latter's death, she begins to switch from one boyfriend to another without much concern for her kids. She runs away when her boyfriends become violent and abusive, leaving her children at his mercy. Tequila disappears from the novel as soon as the children flee the house, not to return.