Fighters are plentiful in the Grand Duchy and have plenty of opportunities for adventure in Karameikos. Traladarans need fighters to keep the small towns and homesteads of the Traladaran safe from invading goblins, orcs and other uncivilized creatures of the forest. On the Thyatian side, fighters are a much admired and respected class, and this holds true for the Thyatian immigrants in Karameikos. The gnomish/dwarven community of Highforge is well fortified and employs many warriors in its defenses against the many humanoid clans that populate the deep forests of the Duchy.
For fighters who choose a to follow an unlawful path, there are many opportunities in the Duchy. For example, there is the Veiled Society, an organization that is perfectly suited to enforcer, thug and hitman-types with a grim outlook on life. Its main center of activity is that of Specularum. Additionally, there is the Iron Ring, a secret organization that engages in slave trading in Karameikos. Suited only to the most cruel and evil, its members include those of all classes, whether mage, thief, fighter or evil cleric. The Ring operates throughout Karameikos, and only a select few know the identity of its master(s).
Congratulations, you have now successfully created a Mystaran character!
For further development of this character, consult your Dungeon Master.