Hey Reinier! Great to already see some stuff
I know you are a busy man, so this came as a surprise 
Ok, let’s get on the subject.
Good idea of you to first explain some ideas you had in mind. I could write about your ideas, but I will be keeping it short if you don’t mind. About the symbiotic interpretation: great thinking. That could be a great step towards a amazing idea/image. The tower-idea is a good one, but I think you can go much deeper. As for the last sketch you provided us with: wow! And yes, I really mean wow. You said you have troubles visualizing emotion properly, well… I think this sketch shows that you can. And it’s just a sketch: good job 
As for the content of the image, It feels like those 2 slaves are trying to relate physically, trying to help eachother escape from their feelings. That’s what you wanted to visualize right? If you could show us why they have those feelings, why and where there is a master… Then we would get a little bit more of a concrete image. Anyway, this would be difficult, If you want to keep it more symbiotic. I hope you find the right solution… I wish you the best of luck 
Sorry for not mentioning the other 2 ideas, I just think your last idea is the best so far.
Cya around!
theChap