Born and raised in Washington, D.C., Grosse began honing his performance skills at the age of 10 years. Spending time at the Summer Musical Theater Workshop, Demetrius was able to practice his skills, in singing, acting, and dance. As a child actor he honed his craft on the stage starring in more than five plays with SMTW. Through training and performance, acting, singing, and dance were all elements of performance that were developed early on as Demetrius began to build his repertoire. Demetrius wasn't always considering acting though. For a time he was interested in veterinary Medicine, coding, and even worked in a barber shop. By 17 Grosse pursued his dreams of acting and studied at Gonzaga College High School. Demetrius then went on and achieved an award for the Andrew Carnegie Undergraduate Grant for artistic merit and later graduated from Carnegie Mellon University with a degree from its School of Drama. In 2002, Demetrius completed a visiting student program in which he finished two semesters of intensive study at the Howard University College of Fine Arts in his home of Washington DC. During July, Demetrius took his craft to the international arena, studying and performing both classical and contemporary drama with the British American Drama Academy in Oxford, England. In the summer of 2007, Demetrius joined Shakespeare Santa Monica. He had performed on the stages of Oxford, England with the BADA group, in Washington DC with The Shakespeare Theatre, and in Cape Town, South Africa with UCT.