[identity profile] sarahdipity221.livejournal.com 2010-08-31 02:38 am (UTC)(link)
Dark Roots by Morpheus fits your request almost perfectly. It's very well written and pretty lengthy. You can find it here: http://morpheusqaf.com/DarkRootsIndex.html

I also really like besame_bj's fic Mirror which is also lengthy and has several sequels. In this one Brian still has the same dad but finds out he has a twin brother who was given up for adoption. Here is the link to the first chapter: http://besame-bj.livejournal.com/26956.html

Hope this helps!

[identity profile] mysid.livejournal.com 2010-09-01 01:12 am (UTC)(link)
I'll second the motion on both of these.

Although Mirror doesn't technically meet the conditions of your request, it does meet them in spirit. As the fic progresses, the adoptive father of Brian's twin eventually takes on the role of father to Brian as well. Brian does indeed get the family he deserves.