Oh, absolutely, they are very dual in how they express emotions. They can be passionate, and loud, and dramatic, and not hide it from each other, at least not when it's about emotions like anger or frustration. Melancholy, on the other hand, regret, and genuine, quiet seriousness - they are both quite capable of that, but it takes a lot for them to show it. So yes, still plenty of barriers there for us fanfic writers to break. :)

Which reminds me of how I heard slash fic described for the very first time: on TV, by a Kirk/Spock shipper who said that what slash authors do is take, for example, the scene from STII where Kirk watches Spock die, and remove the wall. I still adore that description - it's a lovely way to explain the concept of slash without being at all judgmental about it.