Harry had been suspicious of Draco for two days, after watching him accept a scroll from a skinny white bird, read it quickly, then promptly rip his book in half (rather, he ripped his book in half twice, after mending, then ripping it apart a second time for good measure). Telling Ron of his suspicions had launched the red-haired man into a full-blown investigation, which was not good for morale, as he’d become quite snippy over the previous two evenings.  