Life seems but a quick succession of busy nothings

I think I am beating a dead horse here (i.e. Dumbledore = Uber-Manipulator), but I was thinking about the Dark Mark recently and have made some assumptions that I'd like to share.

Quite possibly it's pauraque's re-reading of GoF which triggered this thought, because I can't otherwise explain what made me wonder about the Dark Mark and its implications at this stage. GoF is an old hat, and I should rather have continued writing my ideas on postHBP!Bill, but there you go. This theory appeared from thin air and required being written down.

I've always worked on the vague premise that the Dark Mark triggers reactions of other Dark Marks in its vicinity. It's not in the text, but what is in the text is:

"It was a means of distinguishing each other, and his means of summoning us to him,"

says Snape when explaining the Dark Mark to Fudge in Chapter 36, The Parting of the Ways, in GoF. But how exactly it is used by Death Eaters to distinguish each other?

The books imply that all wizard robes have long sleeves, which sort of rules out the possibility of accidentally spotting another Death Eater's Dark Mark. Besides, as the Dark Mark tattoo features the same motive as the Dark Mark spectre that is used by Death Eaters to indicate that they've just murdered people, it would not be wise for Death Eaters to flash it at the unsuspecting public, who are familiar with the motive and not very fond of it.

Sneaking up at random strangers loitering in dark corners in Knockturn Alley and pulling up one's sleeve to show them one's tattoo in the hope that they, too, are Death Eaters might work, but is still risky and is bound to be futile. - There are more random strangers loitering in dark corners in Knockturn Alley than there are Death Eaters, and it is not a very efficient way of recognising possible allies.

The Dark Mark might be used in lieu of a password to authorise Death Eaters to enter Dark Revels™. It's certainly very handy for people like Crabbe Sr. and Goyle Sr. who are - as the text implies - not terribly bright and incapable of remembering complicated sequences such as, say:

"The significant owl hoots in the night."
"Yet many grey lords go sadly to the masterless men."
"Hooray, hooray for the spinster's sister's daughter."
"To the axeman, all supplicants are the same height."
"Yet verily, the rose is within the thorn."
"The caged whale knows nothing of the nighty mighty deeps."
"The ill-built tower trembles mightily at a butterfly's passage."

So yeah, flashing your Dark Mark at the doorman instead of rattling down elaborate passwords does make sense - especially when you consider that Lord Voldemort does not seem to select his followers on account of their intellectual prowess.

But I thought - as Voldemort uses the Dark Mark to summon his followers by activating one Death Eater's Mark (Peter's in GoF) to which the other Dark Marks react thus indicating to their bearers that they have to Apparate at Voldemort's side - that it would make a lot of sense for individual Dark Mark's to activate each other, too. If a (masked and robed) Death Eater bumps into another (masked and robed) Death Eater, they know instantly that they work for the same side. I used this concept in The Last Resort, where Snape realises that Peter's just entered the room by the reaction of his Dark Mark.

( What does that mean for GoF? )

My submission for the HP Squick Fuh-Q Fest is up. It's an NC-17-rated Argus Filch/Albus Dumbledore fic. Consider yourselves warned.

Curious how a long beard and hairy toes can be included into hot shower action? Click here.