During Darrow's year at The Institute, House Mars is located in the north in a mountain region and is given two towers to occupy in addition to their castle. The House becomes fractured due to not having solid leadership, with three factions developing; one led by Darrow and Cassius, another led by Titus, and the final controlled by Antonia au Severus–Julii. Through Darrow's strategy, he manipulates House Minerva into defeating Titus, before defeating House Minerva in turn and House Diana shortly after. Another faction develops after this, led by Sevro au Barca, known as The Howlers, though they are loyal to Darrow.
The House undergoes hardship after this however, when Cassius betrays Darrow and takes over as Primus. Darrow is rescued by Mustang and together they begin their own coalition which subsequently defeats several other houses at The Institute. House Mars itself is besieged by House Pluto, and Cassius gives up trying to achieve victory due to his conflicted feelings. Darrow later resumes command and defeats House Pluto, winning his year at the Institute.