but I don't see the whole "Sherlock-continually-breaks-his-brother's-heart" thing really...happening, like, ever.

Oh, well, that's just sort of my own speculation about how their relationship progressed--total personal extrapolation on canon, not at all a comment on BW. I've read some very angsty stories from other authors that take the same line, but I'm open to reading other interpretations, too. And no matter how BW ends up, I do really enjoy your young Sherlock and Mycroft, as they are very enjoyable and make an excellent antidote to too much adult angst.

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. :)

I look forward to reading it!