There are a few relation states that I find missing in Drox:
1. A not-quite-war but not-quite-peace state aka flash conflicts. A race that dislikes another race but hasn't declared war on them should be able to occasionally destroy their ships, without triggering all-out war. There would be a small penalty for each attack, but if happening rarely enough, a war should not break out. This would also allow you as the Drox to engage in piracy, attacking ships for profit without triggering an all-out war unless you overdo it. As a privateer, you may occasionally attack a race's ships, but then do some favors (quests) for them and they'll 'forgive' you.
2. War fatigue. After being at war for a long time, assuming sufficient losses are incurred, an AI should sue for peace. It could offer to trade money or even a few planets if necessary.
3. Suing for peace. A race that's incurring heavy losses should sue for peace at all costs, begging for mercy, and perhaps offering to become a vassal/tributary. (In fact, this is one of the few situations that should allow for these kinds of arrangements IMO -- doing it randomly feels weird).
Additionally, this may be a good time to put goods of different kinds into the game. Goods (e.g. food, minerals, metals, drugs) would be carried in your inventory and consumed by different planets and produced by others. Prices would change based on supply and demand in the sector. Shooting down good-ferrying ships could causes crises. Furthermore, war is in your interest as a trader, since warring races have more demand for certain goods. You already have the quests for situational goods (medicine and such) -- now you can also add constant goods that are constantly consumed by races.