Oh my god. This is basically the same idea I had for my entry but like 1000000000x better executed. Allowing the characters to stand on each others heads is clutch. I think the fact that the two entities interact to finish the level is more impactful than just hitting a mcguffin switch to allow the other character to finish which is common in this style of game. I think this is what separates Trine and unravel from other 'Multi-character platfomers' and you nailed it.
fantastic entry, great job.