I am thinking of having my resurrected Breton Nightblade join the rebellion, and am unsure of why? Any ideas why someone who uses magic, will work for pay normally unless it is an real important cause or he gets something else out of it, and prefers to knife/slash someone from stealth would join a rebellion for a "seemingly" Nord-only cause.
My non-Nordic characters typically join up with the Stormcloaks for purely practical reasons. Cyrodiil is weak; When they had utterly destroyed the Dominion forces in their territory, they sued for peace rather than continue to fight. Not because they couldn't win, but because if the war continued Cyrodiil would've been crippled, and they would have lost their influence over the rest of the Empire. When the next Great War begins, what's to stop them from giving up once again when things get rough?
A free Skyrim, however, has the will to stand up to the Dominion. And without Imperial taxes sapping their resources and Thalmor spies sabotaging them from within, they can effectively prepare for the war, whereas the Empire is stuck paying tribute to the Thalmor with spies and traitors mapping their every movement militarily. Look at Ulfric's would-be execution. He had been captured by Imperial forces, but the Thalmor somehow found out about it and were moving to interrupt the execution when Alduin attacked.
