What happens if you attack the ships in an allied fleet? Do they automatically turn hostile?
Nothing happens currently. Finding a proper solution is tricky to say the least - there'a always accidents and outright deliberate shooting of allies to take into account (the first thing that popped into Megas' mind, the ever-powerful exploiter he is).
I remember Alex mentioned the idea of having a fleet-specific reputation. Maybe that could be worked into it, where the reputation changes during the battle depending on how much damage you do to the allied fleet.
So if you had a good reputation with the allied fleet, they'll be more forgiving of friendly fire, but if you're fighting pirates and the allied fleet is neutral toward you, they'll turn on you if you so much as nick them with a beam weapon.
The one other thing I'm not so sure about is having other fleets automatically join in the battle... what's the radius on that? Is there any delay before they join?
I think it would be nice to have at least some chance of eliminating them one by one if you're quick and aggressive.