Silver-Green Dragon

Harry and Ginny have a fight while they're visiting San Francisco. Harry goes to a bar, runs into Draco Malfoy, and they end up buuying each other drinks. He wakes up the next day with a hangover, no memory of the night before, a ring on his left ring finger and a silver and green Dragon tattoo on his right arm. What the heck happened? Harry/Draco slash COMPLETE