The story begins at the end of book 5…
Harry stumbled out of Dumbledore's office in a daze trying to process everything he had just been told as well as the consequences of their little trip into the ministry. His emotions were everywhere and he knew he couldn't go back to Gryffindor tower like he was or he was libel to scare someone and be seen as even more of a crack pot than the papers were making him out to be. Without even realizing where he was going he ended up in the hallway that housed the Room of Requirement. He was aware of the fact that he paced back and forth in front of the spot 3 times as needed but his head was too jumbled to form a request so he was surprised when the doorway appeared. Perhaps the room knew what he needed even if he didn't himself.
When Harry entered the room there was a comfy looking sofa sitting in front of a coffee table with two items on it, a photograph and a journal. The first was a framed photo of Sirius and Harry sat down heavily on the couch clutching the frame to him and crying over the loss of his godfather. The tears were therapeutic and he felt some of the weight lift as he gently set the picture back on the table. He was glad that the room had given him the picture as he knew he never would have cried in front of his friends. He reached forward and grabbed the journal off the table to find that it was Sirius' and the tears began anew.
Before he was able to start reading Dobby popped into the room and pointed out the clocks on the wall and explained that for every hour he spent in the room only a minute would pass outside and that the room would take care of him until he was ready to leave. Harry did some quick math and determined he could stay for a month and still make it to the Great Hall for lunch so no-one would worry about him. His heart was aching terribly from loosing Sirius and from Dumbledore keeping so many major secrets and he knew he wouldn't be ready to face everyone for a while. He decided to stay and start to read Sirius' journal. He would figure out what else to do with the extra time later. So he opened the journal to the first page and was surprised to find a note to him.
Dear Harry,
If you're reading this then I am gone. I'm sorry for leaving you pup and I hope that however I went that it was doing something to help you or the war. Don't morn me too long. I have been miserable stuck here in this house and I still feel the years of Azkaban. Be happy for me as I am finally free and with your parents. The only times I have been happy these past few years where when you were around. I love you Harry, you're the son I never had and I wish all the best for you. There are many things that Dumbledore has kept from you and I have written all that I know in here for you. I was hoping to be able to tell you in person but this will have to do. Don't cry when you remember me, but live every day to its best and try to have some fun.
All my love,
Your Godfather Sirius aka Padfoot
Harry began the journal after his tears stopped. By having the journal it finalized that Sirius was really gone and he had been trying to believe it wasn't true. The journal started after his escape from Azkaban as a way to try and get his mind back in order. Harry hadn't realized how much damage the dementors had done to his godfather, but then he didn't remember him from before then so he had nothing to compare to. One of the passages caught Harry's attention from after he helped Sirius escape on Buckbeak. It seems he stayed with Remus Lupin for a while and it was the transcript of their conversation.
"I can't believe he was able to conjure such a powerful patronus," Sirius said with pride. "I didn't realize just how powerful he must be."
"I don't get it though Pads," Remus said to his long time friend. "He's never shown that kind of power before. He barely scrapes by in most of his classes."
"I don't understand; he's very smart. He has to be; James and Lily were top of every class!" Sirius said.
"He doesn't try at all and his homework looks rushed and un-researched. I understand that he spends all his time with the lazy Weasley boy but he should be able to do so much better without any real effort. It's like he tries to do poorly," Remus told him.
