D4-K4 values balance, it has a moderate regard for few organic beings, harboring a generalized distrust while analyzing the chances they will try to capture and enslave it. According to some he has spoken to in his existence, the Republic was evil, to others the CIS, and the Jedi. It learned quickly that only people who share opinions consider one another in the right, and so it looks objectively between each to see the merits, and flaws, of them. Criminals steal and keep more than they need, the needy demand more than they require to compensate. Only those who actively strive to hold no sides are in balance, as they give and take as per what is best for them, and their homeostasis.
Embracing this idea, D4-K4 is studying to trust some organics and better understand the ones it should avoid. An individual drive for balance is rarely achieved, and even D4 acknowledges that even it can, and will, fall out of line with its ultimate goal.
The 'plight of the droid' is not a major concern to D4, some droids are free, some are not. While it sees some hypocrisy in sentients who express distress/disgust/etc. about other sentients being in a similar circumstance, it acknowledges it's not a concern to spend overmuch time on, understanding a single figure (especially a droid) could have little effect, and the movement for free droids is so small that to join them would be just becoming part of a slightly larger pebble incapable of creating sufficient ripples. It has no problem being used as an example of free droids, but that is its current opinion, and can change later.
D4-K4 was 'born' when several B2 droid units were salvaged after the Battle of Geonosis to build a single unit. Designated D4-K4 because it was successfully built from four separate B2 units, and its cognitive module came from the unit that had made four consecutive kills, including one Jedi, before it was taken down by another. D4's decades long existence has included a guard droid for smugglers, a pirate slave-automaton, Free Droid with status ratified by the Galactic Empire, and registered bounty hunter for over thirty years with middling success and not a likely reputation other than one of a number of droids like 4-LOM and IG-88 that had gone bounty hunter.