Marcus was born to a Starfleet family. His grandfather was a first officer who was killed on an away mission when Marcus was six years old. Subsequently, his parents both accepted positions on Starbase 16, a safe assignment designed to protect their family from any further trauma.
Marcus inherited a scientific mind, but something of a rebellious, exploratory streak from his grandfather. That led him to apply to Starfleet academy when he was eligible and his aptitude for science served him well at the academy. He found that we did well in subjects that he could relate to science, and even performed well in security related areas, mainly due to a determination to avoid the fate that befell his grandfather. He had little interest in piloting or the psychological sciences though, and allowed his grades to suffer in those areas.
Upon graduation, Marcus was assigned to the USS Tesla, a science vessel. He did his job well, and proved to be an asset to the vessel. He began work on his pet project, which he named the survival suit, a lightweight, user friendly way to protect and enhance the performance of away team members.
After a while, Marcus became dissatisfied with the relatively safe, slightly routine nature of the Tesla’s assignments, and requested a transfer to somewhere more challenging.
The Hawaii's assistant science chief is young and enthusiastic about his chosen field. He was the potential to be brilliant, but needs that brilliance channelled properly.