Of course, if you went far enough back, his mother's side was his father's side.
*dies*
OK, so if I'd read this before I knew it was you, I might well have known it was you as soon as James started writing lines. Because you are, in addition to being an awesome HP writer, an awesome Good Omens writer, and there was something so very Good Omens about James writing commentary in his lines.
This story? Is awesome and so fucking hilarious. I love the different versions of the truth. And McGonagall's silver. And the hot boyfumbling. And pyro!Sirius. And the drunk!singing. And lines like this: "Potter and Black cheek you constantly. Please refrain from setting them on fire, whatever the provocation." If I quoted every line of this fic that cracked me up, my feedback would be about 50 comments long. Love it.