Oh, this is good! I like this Sirius.
Love how Mrs. Black actually thinks she can subvert the Sorting and have Sirius put in Slytherin.
And your choice of names: 'Malevala Nott' and 'Finn Potter.' Yum!
Mrs. Potter is rarely dscribed in fan-fic. I like your version of James' mum--er--mother. (Yes, that fits her better.)
Favorite lines, because they reveal a lot about the character in a short bit:
..he rather liked Lily himself.
"Your blood-traitor Gryffindor brother can do it right, so why can't you?...Get to your spell books, boy!"
"I'm not like my family, ma'am..."
"Dear old Mum's finally flipped..."
Thanks for a great read. I hope to read more of these soon.