Since Evan and William are friends, Evan's more than welcome to be William's sidekick if you're so inclined? If there's someone it'd work better with (an older Slytherin, etc) that's cool, but I just thought I'd throw it out there!
And if we can find a protective big-brother type, I can volunteer either Chloe or Juliet as the victim. Though he'd be more likely to get a rise out of Chloe than Juliet, as she just tends to ignore people.
And Chloe could definitely fit The Enemy for Lucy as her father tried to kill her (well, not literally, but as far as Chloe's concerned, and that's what she'll tell everyone). I can see her forgiving some IS members, but Lucy's incredibly unlikely to be one of them.