Marilynn "Mari" Mariella: she/her, pansexual, ISTJ, hates when her boss calls her "Mar-Mar". Marilynn was the daughter of a chemist who worked for the mafia, making untraceable poisons. A mistake on her father's part caused a chemical explosion, killing him and her mother. A fortune in damages. a fortune that needed to be paid off.
The don would have threatened her next of kin to pay it off, but Mari didn't want to endanger the rest of her family, so she offered herself. She proposed she study what her dad learned to become a chemist herself (giving up her dad's hope of her becoming a toxicologist to save people from poison).
The don decided to give her a deadline: make money for him as a chemist...or make money for him as an escort. Needless to say, she ran out of time, fell deeper in resentment and gave him a taste of his own poison, killing the whole group and herself with them.