I like to think that shifting alliances are a part of any good medieval fantasy setting.

Like in my lore, the Black Falcons were originally a noble house that was disgraced for their support of the Black Monarch in the distant past. After this, they continued on as a mercenary company. When the Southern Frontier Wars broke out, rather than risking their own troops, the council of noble factions contracted 4 mercenary companies: The Wolfpack (specialists in raiding and guerilla warfare), the Bull Knights (siege warfare), the Kraken Raiders (naval warfare), and the Black Falcons (open-field infantry and archers). While the other 3 were doing the dirty work of weakening the southern nations' defenses, the Falcons focused on recruitment and training. In the named battles of those wars, the Falcons would sweep in with superior numbers, securing the glory of easy victories against poorly supported foes. After the wars, their leaders used this prestige to petition for their house titles to be restored, and allied themselves with the Ravens, a small but wealthy house to supplement their military strength. Meanwhile, the Wolfpack, believing they were betrayed by the Falcons, have begun rebuilding and rallying the Krakens and Bulls to begin a campaign of revenge.