Harry's Uncle, who had been hitting Harry since he was a small boy, was currently beating the living daylights out of Harry.
Over at Hogwarts the monitor in Dumbledore's rooms that made a lot of noise if anything happened to Harry went off. Dumbledore rolled over in his sleep, humph'ed and hit the device, thinking it was his alarm clock.
Just before he lost consciousness Harry thought "Hey I hope someone will find me even though no one ever checks up on me."
A while later Severus Snape entered Dumbledore's office to bring him some potions and to rant a bit more about how he hated teaching, Harry Potter, the Dark Lord, Harry Potter, the Ministry, Harry Potter, how Dumbledore favored Gryffindors, Harry Potter, James Potter, Sirius Black and Harry Potter.
The Headmaster was not there but an annoying noise was blearing from the bedroom. Snape snuck in to find Dumbledore sleeping and his alarm clock making a lot of noise. Wait, it wasn't his alarm clock. It was a clock that kept track of Harry Potter.
"Oh gosh darn it," Snape said, "I shall completely voluntarily go rescue Harry Potter, whom I hate, in case he is in trouble."
Snape Apparated over to Privet Drive and walked through the wards despite having the Dark Mark and it being Unplottable and him never having been there before.
After a moment of interrogating Vernon and being as unpleasant as possible to the Muggles he found the beaten up Harry.
"OMGWTF! Harry!" he yelled, "I never noticed you were abused, so was I, I never imagined we'd have so much in common! Come here, I'll take you to Hogwarts and look after you."
Ten minutes later Harry was healed and laying in his bed in Snape's quarters. Snape had spent five minutes completely redecorating and expanding the room for him and even added murals of flying phoenixes and other specifically Gryffindorish things.
"Wow Professor," Harry said, "You aren't really so bad after all, I think I'll live with you during this summer instead of the Burrow, nevermind that you were a bastard to me for years."
"Oh thank you, Harry," Snape said with tears in his eyes, "that means a lot to me. How about I adopt you ignoring that the fact that I'm a spy puts both of us in immediate mortal danger if I do?"
Dumbledore appeared out of nowhere. "I'm so glad you get along, now that you adopt Harry you of course don't have to spy anymore, and I hope you don't think I love Harry more because I never let you stop spying when you didn't like him yet."
"Of course not Albus," Snape nodded and Harry jumped into his arms.
After a group hug they all lived happily ever after.