Overview
Marcus is Vianna and Julian's father, an adult level eight mage from Brighthaven. He knows Isaac through Damian and accepts Isaac's harsh training of Vianna at Radiance Prime Magic School, even after Vivian objects.
History
Marcus lives in Brighthaven with Vivian, Julian, and Vianna. When Vianna struggles at Radiance Prime, Marcus insists she give Isaac's class one more year and agrees to consider another, theory-focused school only if that year brings no change. He later admits he had an idea why Isaac's training was so severe.
When Alistair moves against Vianna and Damian dies, Isaac comes to the family home and Marcus leaves Brighthaven with Vivian, Julian, and Vianna by construct boat. Brighthaven's technology was built to defend against Pyrathalor, and Isaac has protected Vianna and her family since her childhood.
Marcus and his family settle in Hengzhou, the capital of Hengvaris. Two years later, Shroudvale shapers attack the city. Marcus, Vivian, and Julian go out to fight while Vianna hides; Marcus and Vivian are dead by the time Kaldaryn's force reaches Vianna after Shroudvale's attack on Hengzhou, leaving her shattered by the loss of her parents and brother.