Harry was sitting on the windowsill of his bedroom at Number 4 Privet Drive looking out of his window and contemplating how fucked up his life had become. His uncle had raped him again that night and had given him the worst beating Harry had ever received. He was crying silently wishing that things were different, that his papa was there to protect him like he should be.
His papa of course was Severus Snape. James and Lily Potter were never married to each other; it was a ploy to stop Voldemort from finding out Severus was a spy for Dumbledore. James and Severus were married at the end of their seventh year, a fact known only to Dumbledore and Lily. 2 months later Severus conceived Harry and 9 months later Harry was born. Lily and James pretended to get married and have a son to protect Severus and Harry. A year later the prophecy was created and Harry had to go into hiding, something Severus could not afford to be discovered by Voldemort. He planned to remove all his memories of his marriage to James and of his son to protect him. James persuaded him not to and told him that he, Lily and Harry would go under the Fidelius. The events afterwards were too painful to remember. In the end all that mattered was the fact that Severus thought Harry didn't remember but he did. He remembered all of it. He remembered life at the Dursley's, being beaten up by Vernon and Dudley praying to every god known to man that his papa would come but he never did and Harry ended up believing he was dead. Until, of course, when he arrived at Hogwarts and his father was there.
All through his years at Hogwarts Harry forgave his father absolutely everything because he believed his papa didn't know what the Dursley's were like and thought he was safe there, especially when Harry knew that Voldemort would eventually come back and that he would have to destroy him. Oh yes, Harry always knew he had to destroy Voldemort and had always been a natural occlumens. Why then do you ask did he receive a false vision of Sirius in danger? The answer to that is, he had let his father see certain images of his past in the hope that his father would realise how much Harry needed him. His father did not even try to teach him properly, he literally raped Harry's mind lesson after lesson and Harry's shields were weakened enough for Voldemort to discover that Sirius was one of the most important people to him. Harry was devastated and blamed his father because he did the one thing Harry couldn't forgive.
So here was Harry at his window wishing he were at Potter Manor with his family. He missed them: his fiancée Neville Longbottom and their 1 year old daughter Sophie (Harry carried her), his brother (blood ritual) Ron Weasley and his fiancée Luna Lovegood, his sister (blood ritual) Hermione Granger and her girlfriend Ginny Weasley, his godmother Poppy Pomphrey and his second godfather Remus Lupin. They all knew the truth about Harry's parentage. Harry had told them all at the end of 3rd year. He'd needed them to know that he had known about Sirius's innocence all along and thus ended up telling them the truth. He needed them now but most of all he needed his godfather. He needed Sirius.
Suddenly he heard his uncle slam into his room. He was flung into the wall and his uncle grabbed him to pull down his trousers but he was stopped. A familiar grim like dog stopped him.
"Sirius? Y-you're alive?" Harry whispered and the dog turned back into Sirius. Harry flew into his arms and started crying hysterically. He fell asleep in the arms of his beloved godfather who then apparated them both to Harry and Neville's bedroom at Potter Manor. He explained to Neville what had happened and went to tell Remus he was alive before preparing for a meeting with the man responsible for most of Harry's suffering: his papa, Severus Snape.