About a week after Sirius' death, Lupin talks to Sirius' spirit. This is what I believe he might say...
This is the story of teh night when Sirius Black ran away from his family at the age of sixteen.
Sirius' POV of teh night Lily and James dies and when he faced Peter afterward. Rated PG for a little bit of language.
This story explains how James was able to get Lily to go out with him in their seventh year.
Harry thinks of Sirius and the rest of his friends this year. He realizes the loyalty that they have toward him and he finds great stregnth in is friends.