The Starks are a House old in honour, plunged of late beyond redeeming into disrepute. Their old Lord, the Usurper's friend, a weak and rotting captive; their young Lordling, a bloody-handed and dishonoured murderer, a forsworn victim of richly deserved justice; their present powers, a mewling child and a maddened widow in the hands and mayhaps the bed of her low-born foster-brother, who once reft her and her sister's, his present wife's, maidenheads.
The King grants to House Greyjoy whatever justice it means to claim from this perjured and ailing House.
I'd be careful of what house you threaten, and I'll remind you that only one of us has recently made a large noble family go extinct.