Thank you for your question, and thanks for using JustAnswer.com. Are you the new beneficiary of the inherited IRA?
If you inherited the inherited IRA then you could make the decision as to whether to take the RMD or close the account out in 5 years, based on when you inherited the account
so, your brother missing his RMD for 2012 would not mess things up for you
However, if the inherited IRA is remaining in his estate, then there's no way to fix not taking the RMD during 2012.
The estate cannot take the RMD now, as it is too late