This assignment is most likely already completed and my answer may not be helpful to you, but perhaps it will be to others in a similar future situation?
Ah, creature / character vocals! A sound designer's dream, a sound designer's nightmare. And to make matters even more complex, the character is a machine!
There are so many avenues to explore, the possibilities are truly endless. But the place to start is the STORY, the script. That is where you can learn about the character and what makes it tick.
Why does it have emotions? What does it do when it emotes? Is it fast or slow, large or small, man-made or alien? Can it be killed or is it immortal? Does it actually have a language?
For your particular situation, your palette may be a bit restricted. Since the protagonist is a quadcopter drone, you'll most likely need to stick to sounds that it could "realistically" make, ie. rotor spins, power ups and downs, beeps, bloops, etc etc. That said, there is a range that you could explore there, in that drones are very tonal in nature and also have a cool stuttery propeller texture that can be manipulated.
If it were me, I'd start by recording several brands of drones at the highest rates available to you (24 bit 192kHz is what I'd record). After I'd mastered the sounds and put them into the library, I'd begin experimenting with varispeed and a host of plug ins, possibly granualizers and pitch / frequency shifters, and just see what the material has to offer.
Once I've hit upon some cool stuff, I'd try to make a vocabulary for this character, a variety of sounds that convey particular emotions like anger, happiness, sadness, death. The start playing them for your director; chances are he/she will have feedback and, voila, there's your collaborative relationship off to a running start. It's crucial that you get your material in front of the director asap so that they can get on board with the design and "own it" as a part of the story, rather than merely an add-on that was done in post.
This can be an incredibly frustrating, as well as an incredibly rewarding, experience - buckle up and get to work!