Aluminum Christmas Trees: At first, a shotgun silencer seems like a Hand Wave to prevent the neighbors from hearing Vernon shooting Hedwig, but shotgun suppressors actually exist, and while the sound of the shotgun blast is still rather loud, it's safer for the shooter's hearing.
Badass Decay: Neither Harry nor his friends from the wizarding world can do anything against the Dursleys even when his life is in danger.
Vernon crosses it by beating Harry repeatedly and ultimately causing his death.
Not to mention, killing Hedwig in Harry's backstory.
So Bad, It's Good: It may be listed as Angst/Drama on FanFiction.Net, but not everyone is going to read it as such. The story doesn't give a damn about continuity, characterization, or common sense; but it can be unintentionally hilarious nonetheless.
