I agree with Fenn, fully.

It might seem hard, but just use your imagination. Honestly, if I would make him seem stupid at the beginning, while working for the nobles, but during his time as a servant(or whatever), have him research and what not, studying every aspect. I assume this kingdom is high tech(I didn't really read it all). And if so, maybe this 'Angel' could possibly be one of his defective cyborg(still cliche, but eh), who kind of drifted away. Perhaps you might believe she has a 'mother' but in actuality, it is illusion in itself, that the scientist put in her 'mind'.

And if you are thinking it, I wouldn't do the whole, 'Guy falls in love with Angel'. It is kind of cliche, as stated before. It is nice, but it is like a piece of gum you love. You like it for that short while, but then you grow tired of it.

Anyways good luck.

If you want, you can look at my thread or others, to get ideas of story plotting.