Bonnie Lockhart is an attractive woman, a single mom to Mimi and her siblings since being abandoned by her husband. Bonnie is a smoker who's been trying to quit for years. She wears a nicotine patch, but lights up a few minutes after she puts it on. She is jealous of all the families in Salem whom she perceives as luckier than she is: the Bradys, Hortons, and DiMeras. She speaks ill of them behind their backs, but lays on the charm when she's in their presence. Her relationship with her daughter Mimi is a loving one, although Mimi sees through her mom's victim act and is disapproving of her schemes.

Bonnie's always had plenty of ambition, but never any luck and she resents the hell out of it. She feels life is unfair to her and her children and she's always searching for a way to improve their lot, as long as it doesn't take a lot of effort on her part. She cleans houses for a living, but is always working on a get rich quick scheme. She will drive miles and miles to play Mega Power Ball, even if she doesn't have the money for gas. She has tried many a self-help seminar in hopes of a way to turn her life around, but never follows through. But this happy-go-lucky schemer never blames herself; she always has an excuse, always feels she's done everything right and it is life that is letting her down.

After pursuing Mickey Horton relentlessly, Bonnie was thrilled when she finally got him to propose. She hurried him to the altar, convinced that if she didn't they would never marry. As they returned back to the house after the wedding, they were greeted by Maggie, Mickey's first wife, back alive from the dead. But rather than feel threatened, Bonnie felt only confident. Because Maggie had been declared legally dead, her marriage to Mickey was null and void, so Bonnie was the only legal Mrs. Mickey Horton. The three live together in the house, but Bonnie is determined to be Mickey's only wife.

When her daughter Mimi came to her telling her she was pregnant, Bonnie encouraged her to get an abortion, telling her that having children too young would ruin her life (like she felt it had ruined hers), but when Mimi developed an infection after the abortion that rendered her infertile, Bonnie was devastated. Things went from bad to worse when Mimi was arrested for assaulting Jan Spears and sentenced to spend years in prison! Luckily Mimi was soon exonerated by a video showing she was nowhere near Jan at the time of the accident, but Bonnie didn't get much chance to enjoy her daughter's freedom before Mickey told her that he had decided to return to Maggie.

Once Mickey ousted her from his life, Bonnie immediately went back to scheming for a new man and found herself very interested in a newly-single Roman Brady. When a skeleton was uncovered in Salem, Bonnie was frantic to keep the skeleton's identity from becoming known -- it turned out that the skeleton belonged to her former husband, David, whom Mimi had accidentally killed during an argument. Bonnie convinced Mimi to let her take the blame for David's death and went off to serve her time, while Mimi left Salem with her younger brother Conner.