I'm going on vacation, (2 hours and 15 minutes and counting!) and I won't be checking my email (or MySpace). So I thought I'd leave you with some thoughts I've been chewing on for a week or so while I'm gone.
In HBP, Harry finds the fake locket Horcrux with a note to Voldy from the mysterious R.A.B. Lets assume for all intensive purposes that R.A.B. is Regulus Black, Siriuss little brother. [In fact, according to Red Hen Publications, Rowling has tacitly admitted as much.]
We know that Voldy had ordered a death sentence for Reggie. But why might he have done that? Well, from what we know about the Dark Lord, Reggie a) found out something secret about our fav villain, b) pissed him off, or c) scared him. But lets reserve that last option for Dumbledore.
Quite possibly he pissed him off, by deciding not to be a DeathEater anymore. But why doesnt Voldy just punish him they way he does other disobedient or lazy DEs? Maybe because Reggie also found out a secret. Lets take a look at that note (not in diamond form as in the books, but use your imagination):
To the Dark LordI know I will be dead long before you read thisbut I want you to know that it was I who discovered your secret.I have stolen the real Horcrux and intend to destroy it as soon as I can.I face death in the hope that when you meet your match,you will be mortal once more.R.A.B.
Weve all assumed that the secret referred to in the note is that of the Horcruxes. But maybe not. In fact, Voldy has bragged to his DEs about going down the road towards immortality farther than any other witch or wizard. Is it such a stretch to think that maybe hes entrusted the hiding and protection of said sacred objects to very loyal DEs? Possibly Bellatrix? Consider Spinners End in which Bella brags to Snape about being entrusted in the past by the Dark Lord with his most precious Very curious.
Also, just because the subject is banned from Hogwarts, does not mean that there arent books somewhere that contain information on Horcruxes. Maybe the Blacks had such a book or two in their library. Reggie may have already knew what a Horcrux was when he might have heard Voldy bragging about immortality or Bella boasting about Voldys Most Precious. It wouldnt have taken him long to put the two together to make four.
So what was the secret?
Voldemort is really half-blood and not the pure-blood he claims to be.
But why should this have mattered to Reggie?
Consider the Black family for a moment. They prided themselves on how far back their pure-blood line goes. Mrs. Blacks portrait rants and raves about mud-bloods and blood traitors in her house. Their family motto is Tourjurs Pur (always pure).
So Reggie discovers that Voldemort is really a hypocrite and begotten by a Muggle father. I cant exactly say how he found out but maybe it has something to do with the fact that his mothers, Walburga Black, time at Hogwarts overlapped with Tom Riddles. Anyway, this information made him so intensely angry that he could no longer be part of the fraudulent team.
Ding ding ding! I think weve found a winner.
Reggie threatened to reveal his secret, and Voldy couldnt allow him to continue to live. Reggie, knowing that his head was on the proverbial chopping block, set out to swap the real Horcrux with a fake one including a note thumbing his nose to the Dark Lord.
So how did Reggie succeed in pulling off the swap? That, my children, is a story for another time.