A possible way to do the music for the opening sequence:

The music that we will incorporate in our opening sequence, will probably be to separate types, one quite dark will the other is quite cheerful the only things that we will have to consider when we do this to make it work would be to have both tracks in a similar key, and also to have similar parts in each track so that when we switch between them gradually, it will not cause distress or sound out of place, instead we want it to fit in with each other so that they can work with the moods of the characters. Finally, near the end of the tracks and the opening sequence we will want the tracks to merge in with each other so as you will be getting to different moods from the characters in the same shots so, the music will have to merge because of that.