MountainBlade said:
Yes, they will ask again. Seeking them out is just as good though. The only drawback of refusing is that your disposition goes down a bit.
I was worried about this too. At first I was asked to become a vassal by the Nord king, who I do want to join, in the long term, but not when he asked - I just wasn't ready. I turned him down, repaired my rep with him (-3 from 61). Then, a couple weeks later, he tried again - This time the message I received said it was "a hand-written note, written by the King himself" ... but I still had to decline, and repair my rep.
Now I've begin my conquest of the Rhodocks, and hope to have 3-4 castles, including a City, in my sway before I go back to the Nords and say "Look what I've got, let me join you" ...
... With a high rep, the King should offer me more of the lands I conquer for him as we go along, too.
And a footnote on all this - Holy crap, Nords are gross at sieges. They might not do so hot at range, but a handful of them at the top of a ladder is a scary thing - My 45 Nords (Warriors, Veterans, and Huscarls) obliterated a garrison of 55 Rhodocks with only 13 wounded and no deaths. I barely helped, as this character is half archer-half fighter, and when I ran out of arrows, I couldn't get to the fight for all the Nords screaming and yelling on the walls. Turn that scenario around, and the castle's under siege, and the Nords still shine, meeting foes at the top of the ladder like it was a blender, just chewing them up and spitting them out.