It occurred to me earlier that it wouldn't be a bad idea to give players the option of assigning one or more heroes to liaise with other empires on their behalf, considering it would give diplomacy oriented empires something else to do with their heroes once they run out of valuable systems to assign governers.

(Especially the Umbral Choir since they have exactly 1 system and have next to no use for fleets once they've scanned every curiosity in the galaxy & completed the Academy quest.)

As to how it would work... a discount on diplomacy actions & bonus on treaty effects that increases passively the longer a given hero has been assigned?