Mack is the young boy who joins Kaim and the group in their efforts to take down Gongora. He is the son of Lirum, Kaim and Sarah's daughter, and the sister to fellow party member Cooke.
Mack and Cooke both agree to join Kaim after their mother died. They feel just as betrayed by Gongora as anyone, and it's more than enough for them to want to take him on. Mack is the younger of the two, who often is submissive to his sister. He misses his mother greatly, which is seen in scenes later in the game. At one point, he and Cooke stole an entire train just to see some lights that might show them their mother again.
While Mack is a descendant of immortals, he is a mortal character, as is Cooke. Mack is a user of Spirit Magic, a form of magic where the user can alter stats, either enhancing them, or weakening them. He provides some great support magic, as well as speed and strength. While he is still just a young kid, he packs quite a punch, and is useful in getting in early hits. He relies on discs for his weapons.