Why did Sirius trust Pettigrew? WAS: Snape investigating Potters' Betrayal

[Carol]

No: HPFGUIDX 186566

Shelley wrote: 
> Replying to my own post, just add some more canon to this line of thought:
> Snape and Karkaroff know that Voldemort is growing stronger through their Dark Mark. It had grown cold, grown dead when Voldemort lost his powers, and when his powers regained, the spell starting regaining it's full effect again. It's very possible that when Voldemort became "Vapormort", the spell lost it's ability to be stealthy, meaning anyone could see it. But, I doubt highly that it was visible to anyone but a Death Eater in the period before Voldemort's fall.

Carol responds:
I agree that we need some explanation for why the Aurors didn't just examine the arms of suspected Death Eaters and round them up, but I don't think it's a spell concealing the Dark Mark from everyone who isn't a Death Eater. For one thing, Snape shows his Dark Mark to Fudge trying to prove to him that Voldemort is back. Fudge recoils in horror as if he's never seen one before (I'll get back to that in a second), but the Dark Mark is clearly visible to him, to Harry, and to everyone in the room. Snape tells Dumbledore that his Dark Mark and Karkaroff's have grown darker now that Voldemort is returning, and he tells Bellatrix that they all knew for that reason that the Dark Lord had returned.

When Voldemort vaporized, in contrast, the Dark Mark--far from losing its power and being visible to anyone--became so faded that the Death Eaters (except for Bellatrix and her cronies, who refused to believe it, and Snape, who knew better) believed that he was dead. (Snape claims that he also thought that the Dark Lord was dead, but he's lying to Bellatrix as he must also have lied to LV.) 

So if the Dark Mark becomes more visible when Voldemort is strong (and actually burns black when he's summoning the Death Eaters) but fades into invisibility, or nearly so, when he's vaporized, why didn't the Aurors check suspected Death Eaters for Dark Marks? Of course, by the time some of them were actually arrested, Voldemort was already vaporized, and later, when Fudge was denying that Voldemort was back, the DEs who got off by claiming the Imperius Curse (after their Dark Marks had faded) went back into society and became respectable citizens, some of them (Malfoy) on the board of governors of Hogwarts, others (e.g., Macnair) working for the MoM.

My theory, and it's just a theory, is based on Fudge's reaction to Snape's Dark Mark. He acts as if he's never seen such a thing before. (Of course, he's seen the Dark Mark in the sky, but, apparently, he's never seen it burned into someone's flesh. Also, Snape says that the DEs used it to identify themselves to each other (as Karkaroff testified, nobody knew who all the DEs were except Voldemort himself). If that's the case, the Dark Mark may have been a secret known only to the Death Eaters (and to Dumbledore, once Snape became his spy). That's the only explanation I can come up with as to why it wasn't easier to identify the Death Eaters.

I still think, though, that Peter Pettigrew wasn't a DE while he was a spy. The suggestion that he was rewarded with a Dark Mark after he betrayed the Potters is a good one. The other possibility is that he received his Dark Mark after he created the horrible baby body for Vapormort. We know that he could wield a wand. He tortured and Legilimensed Bertha Jorkins and then killed her; he also killed the old Muggle, Frank Bryce. If he could do all that, he could certainly give Peter a Dark Mark (the better to keep him in line).

At any rate, that's the best explanation I can come up with, but I wish that JKR had made the operation of the Dark Mark clearer in all respects, not just that one. We don't know exactly how they communicate, but it seems clear that Voldemort can send messages to the DEs as a group or to individual DEs, and perhaps they can send them to each other or to him as well (beyond touching the Dark Mark to summon him). It seems to be somewhere between a dark and silent Patronus and an enchanted coin.

Carol, also wondering how Draco could get complex messages onto something as small as I imagine a galleon to be