Harry laid on his bed in the smallest bedroom of Number 4, Privet Drive. He was angry, sad and so much more. Sirius, his last chance to get away from the Dursley's- for a family, is dead. Murderd by his cousin Bellatrix Lestrange while trying to help him, Harry bloody Potter.
Harry knew that Sirius woudn't blame him but he blamed himself. He should have known beter then to trust his dreams, Kreacher and even Dumbledore whom let him down time and time again. The only adult who was willing to put him first is dead and Harry didn't know what to do.
Voldemort is back in the open in all his snake-like glory, Magical Britain was pro Boy-Who-Lived again, Dumbledore expects him to kill Voldemort because a drunk made a Prophecy that both the Headmaster and Dark Lord believe in and meanwhile Harry is back with his magic hating relatives.
He doesn't know what he can do against two adult wizards who have decades of experience while he isn't even finished with school but one thing he does know, he won't be able to defeat Voldemort with 'the power of love' as Dumbledore told him.
He needs a plan of action and he needs it soon. But how could he do anything while he was stuck at the Dursley's? Dumbledore said it was the safest here for him and Dumbledore knows best.
Wait a minute...
Dumbledore knows best? Since when?! And why does Harry have to stay with people who hate him while there is a house that is way safer for Harry?
Sirius had made Harry his Heir and so Harry is now the owner of all what the Black family owns. He can go the the Black town house! While the Fidelius has fallen, the Black wards should still be strong. Sirius would want him to get away from his relatives.
It would be perfect. He would have access to one of the biggest private family libraries in the country and perhaps could he even do magic there! Now how to get there without the Order stopping him and sending him back?