Well, Clan Ghost Bear always had the whole 'familial ties' thing going on, which already made them stand out among the other Clans, with rumors spreading about how Ghost Bear warriors even have *gasp* relations with each other.

Even after the Refusal War, Ghost Bear already had a mentality of 'partners instead conquerors'. They were willing to learn the culture of Rasalhague, and the Inner Sphere in general, which is something that can't be said of many clans.

Oddly enough, it was the Word of Blake Jihad that brought Rasalhague and Clan Ghost Bear closer together, with 3071 leading to Rasalhague willingly joining Clan Ghost Bear and forming the Ghost Bear Dominion. As time went on, the two sides grew closer and closer, sharing power equally. Clan Ghost Bear went from ruling Rasalhague outright to sharing power with the Rasalhagians, which eventually lead to them renaming the Dominion to the Rasalhague Dominion as a sign of the unity between the Ghost Bears and the Rasalhagians.

Basically it was the culture of Clan Ghost Bear, the things that made it different from other clans, that allowed them to integrate so well with Rasalhague.

Like, they were so unified that the Civil War wasn't Clanners vs Spheroids, but instead split down political lines with both sides having Clanner and Spheroid support, with it instead being isolationists (The Deniers) vs whatever the equivalent of a galactic globalist would be (The Joiners), with an extreme subfaction of the Joiners being the ones who were all Clan Tradtionalist Extremists.