Ryan is Grace's youngest and adopted son. She loves and cares for him deeply.
Mark is Grace's oldest son. She loves and cares for him deeply. In Let's Be Idiots!, he is seen to be protective of guys she dates, such as Seth Harper, possibly as a result of her and Mr. Walker splitting up.
Seth and Grace dated before. They first met in Let's Open The Monster Heart!, when a fire forced them and the rest of the employees, along with Ryan and his friends, out of Harper Futuristics. After Grace grounded Mark for snooping in her business, Seth took an interest in her and the two agreed to go out on a date. However, he later revealed to her that he's behind the monsters, and because of this, she lost interest in him.
Davis Walker is Grace's former romantic interest, revealed in the end of Let's Get The Big Bad! when Ryan found his adoption papers. It can be implied in Let's Open The Monster Heart! that he left Grace and remarried years ago.
- Her first husband Davis Walker remarried years ago.