Well, I think I never explained the Blood and Water universe in English (my fault), but I don't see the whole "Sherlock-continually-breaks-his-brother's-heart" thing really...happening, like, ever. The way I see it, Mycroft's EQ is a bit too high for that. If anything, Sherlock is the more sensitive one and thus more prone to...well, I wouldn't say angst, but hurt and rage, hence the drugs later, etc etc etc.

Overall, I think their relationship really progresses through BW as both character matures. I think I haven't really touched upon Mycroft's own immaturity as a cause for the rift, but hopefully I'll get a chance to do so. :)