He was in fact making use of the House-Elves -- nice catch, that -- but, well, chalk it up to author error. There was going to be a scene in class with the fifth-years told from Doug's point of view where they would have been subject to the pillows. The House-Elves' help would have been mentioned during it, but I cut the scene for a couple reasons (one of which being that it buggered up the calendar) and I forgot to transplant the explanation.
-- Bob
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Then the horns kicked in...
...and my shoes began to squeak.
-- Bob
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Then the horns kicked in...
...and my shoes began to squeak.