Tristan was born to Morgana and Jarran McCallan and was always overshadowed and demanded to rise above his father's accomplishments as was the McCallan way, but even into his thirties he could never some way to become worthy of his right to be Marcher. He studied and learned the ways of mounted combat from the experts across Gilneas as well as his own McCallan tutors.
After the rumored death of his father and thrust into the spotlight with no accomplishments, he begrudgingly had to take the post of Marcher Lord. The disrespect of his peers nearly had him at the throats of his father's greatest allies. It was from this very disrespect he founded an elite force of shock cavalry that shook the foundations of mounted combat in that era. His peers fell in line, either from fear or respect, he had finally attained the right of rule within his house.
Early in his rule he was faced with an incredible challenge given to him by the current King at the time, Aderic II. The March of Hershire had renounced their ties to the Kingdom of Gilneas and announced themselves as Kings of their own land. This was happening while the flames of Larelion had yet to be quenched and the situation needed to be handled swiftly. Tristan took this task and achieved it at great cost to the United Marches of the Plains infantry forces on the hike to the open fields of The Kingdom of Hershire, where his shock cavalry won him the surrender of King Alastan. In keeping to his own kings law, he beheaded the traitor and conquered the mountain, bringing it back to the fold. He was branded by the Hershire people as a King-slayer, and it gradually caught on within the Plains.
When Larelion re-emerged, he only saw it as a bigger opportunity to surpass his father as well as get some well deserved vengeance and security for the glorious kingdom of Gilneas.