Chickens Are Coming Home To Roost

This is another "how it might have gone" type story. What if after the event where Sirius betrayed Moony to Snape nearly getting Snape killed, the Maurders all swore an oath not to ever betray each other ever again and to protect their very unusual pack. What if that oath had been called due in the Shrieking Shack. What will Magic do to the traitor? Possible OOC