I'm kinda working off an idea I read a few minutes ago in the other "I h8 negative medals thread!!!1"
So players can purchase sets of truce/alliance badges. 5 or 10 of them for $1. In a game, you can offer another player one of those badges, indicating that they are in an alliances/truce/friendship. Only those two players can see the badge. Let's say player A agreed to accept a friendship badge from player B
The badge lasts X amount of hours. If no subs are sent from A to B, then player A (who agreed to accept he badge) is given a permanent "trustworthy ally" medal that is displayed in their profile. If A attacks B before the badge expires, Player A is given a "backstabber" medal (or something similar) in their permanent profile. Badges disappear when the time limit is over or the game ends