Quote Originally Posted by Rozanov
Another couple of points:

alliances should mean something.

for example if your ally doesn't aid you (or you don't aid them) when one or t'other is being attacked by a third faction, then the faction being attacked should be able to end the alliance as it isn't doing anything useful.

(or maybe have defensive and offensive alliances. i.e If allied to a faction and that faction attacks another that you're not already at war with then they should be able to demand you join the attack actively or your alliance is at an end. Or if defensive if you don't aid a settlement being attacked before it capitulates thenn that would end the alliance.)
i believe the "offer attack on" option under diplomacy does this for about 15 turns, to some degree anyways. I've gotten the Pope to re-enforce one of my towns under siege by using it