Personally, I began to sign up in Druzhina (then Greys) mostly because I was always the only Imperiale accepted in the roster. UIF had very few roster support so we were able to be accepted en masse, also seemed more fair. Even with us, sometimes they lacked 10 players in important fights.
Then, each time there is a Wolves/Coalition battle I fight against you because of strat politics, I want to make sure you are weakened myself (Rogue and Kinngrimm should know why
). And then, helping the Greys defend their castles and cities against who we knew would become at some point our enemies in a war. It was almost certain Eastern block will gang us so it fits in a war logic. Even though, in big big strategus battles/sieges, there is always the certainty that the 50/50 limit will be reached so it doesnt really matter! Roster support should bring a casus belli only when it is done repeatedly and benefits greatly to one side.
Still, sometimes we fought on your side, when the situation was good for it, we do not hate you particularly, its all in good fun (well maybe some have griefs with one or the other but thats personal stories).
We created a chinese block not only for the show Kinngrimm, it really means that we act independantly. Our interest definitely converges (with UIF) since we decided to try to expand into a Eastern faction. Then if Eastern decides to make this war another Eternal War of total annihilation, it will definitely build support between UIF and us: enemies of my enemies are my friends!
That is completely up to your side to decide.
I hope for a much more geopolitical domination diplomacy on strategus!