Very strict. Don't like the undead, and have discriminatory attitudes towards "monstrous" species such as goblins. Like to guard things and lock up perceived "troublemakers." Other members of cults, such as Grizzop and Azu, don't seem to like them very much. Wear red robes.
After Kafka attempts to conduct a ritual in Prague, the Cult of Mars takes over Prague University, arresting the party, and searching for the university council and anyone associated with Kafka. They guard the entrance to Rome, and seem to have some sort of agreement with the Cult of Apollo that let that cult come look at Rome as part of their paladin initiation rites.
Unlike other cults, they use the Roman name of their deity. The reason for this is still unknown.