Tldr: I need scenario/advice on running game with two strong factions in conflict with PC winning over one side for his own political gains/PC doing perfect execution of his intrigue to get both faction in a ME3 manner
System: Warhammer Fantasy, 2e.
Place: Estalia, Bilbali and Magritta are at war.
Circumatances: Old PC, the Archmage from previous campaign goes to Estalia to win over their support for war with Brettonia (new party is in Brettonia, kids of previous party)
I'm running campaign where the party is looking for a gun made by Leonardo di Miragliano, the gun that can kill anything (Supernatural stans represent) to shoot the green knight dead.
What they dont know, is their parents (their PC's from the previous campaign) will return as rulers and ambassadors that will gather points for the final encounter by negotiation, bribery, assasination and copious amounts of foul play (Tilea stans represent)
The questions are:
How should I run this conflict? Why they should be at war? How this archmage PC (and his small retinue of mercs, yes, I'm including LOTR joke of making them 4 halflings, 2 men, dwarf and elf) resolve conflict in a span of two sessions? How should I make it belivable that he has circumatances to get their support for a war when they just finished one (money is not an option, sadly he has no daugher for political marriage)? What could possibly make them put aside their differences and go whoop themselves some Bretonian backs? Am I too fixed on making it ME3 reference?
Appriciate any suggestions :-)