I think the implication here is that Dumbledore knew all along (or at since since before the beginning of PoA) that Sirius was innocent.
I think this is very possible. He doesn't seem to have to struggle with the concept at all, despite the fact that he only has a very few minutes to talk to Sirius before he goes to Harry and Hermione to arrange his escape. There's no time there for incredulity and the overturning of 13-year-old assumptions of guilt.
Clearly though he can't have had any inkling of what really happened to Peter. Most likely he thought that there was some other dark wizard in the equation, and that what happened on that Muggle street was Peter being killed and Sirius framed by someone else who then fled. I doubt Lupin was his prime suspect, but he may well have thought that he was Sirius's... in which case appointing Lupin as DADA teacher may have been designed to pull Sirius to Hogwarts so that he could be caught in order to talk to him and find out what had really happened all those years ago.
So... while everybody else thought that Harry was Sirius's target, Dumbledore probably imagined that Lupin was. I wonder whether the attempted break-in to the Gryffindor common room and the apparent attack on Ron shook him at all?
no subject
I think this is very possible. He doesn't seem to have to struggle with the concept at all, despite the fact that he only has a very few minutes to talk to Sirius before he goes to Harry and Hermione to arrange his escape. There's no time there for incredulity and the overturning of 13-year-old assumptions of guilt.
Clearly though he can't have had any inkling of what really happened to Peter. Most likely he thought that there was some other dark wizard in the equation, and that what happened on that Muggle street was Peter being killed and Sirius framed by someone else who then fled. I doubt Lupin was his prime suspect, but he may well have thought that he was Sirius's... in which case appointing Lupin as DADA teacher may have been designed to pull Sirius to Hogwarts so that he could be caught in order to talk to him and find out what had really happened all those years ago.
So... while everybody else thought that Harry was Sirius's target, Dumbledore probably imagined that Lupin was. I wonder whether the attempted break-in to the Gryffindor common room and the apparent attack on Ron shook him at all?