My two are 19 months apart, and are opposite gender so that may affect the dynamic. In any case, there are times when they band together and are best of friends because not many other kids understand or can relate to their intensities (for example, they both take "silly" WAY over the top and alienate other kids, but together they have a blast). Other times the intensities work against them and maaaaan oh man do they fight. For the most part, though, they get along really well. FWIW, their personalities are quite different from each other's as well.
