I'm not allowed Graves House. Dumbledore said (and this is
not a direct quote) "If any student in Hogwarts were to be worthy of having their own house, it would be you. You're the most talented and best looking student Hogwarts has ever seen. Unfortunately, when the founders founded this school, they placed a charm on it that meant if any new house was formed, the Headmaster would die immediately. While I would be honoured to die for you, I would not like to leave you with that guilt."
This makes sense so I'll deal, even though it is a shame. I'd already written up a bit for the Sorting Hat to say and everything!
"If for these houses you are too cool,
and you're better looking than half the school
Graves is the place where you belong
so put on this hat and let's move the sorting along. "