Lupin's resignation and the legacy of hate

[Irene]

No: HPFGUIDX 99689

I'm rereading the PoA (to get the last uncontaminated joy :-) ),
and I noticed something for the first time:
Lupin gives two completely different resignation stories to Hagrid and 
to Harry.
It seems that to Hagrid Lupin presented it as his own noble  decision -
can't risk it happening again. But talking to Harry, it's all Snape's 
fault. He even chooses the motive for Snape - as ugly as possible, of 
course. How does Lupin know that order of Merlin was the last straw for 
Snape, not the fact that he forgot his potion? It seemed like throughout 
the school year Snape  stopped just short of spoon-feeding this  potion 
to Lupin. As good a foundation for the last straw as anything.

How poor Harry can achieve a working relationship with Snape if 
responsible adults in his life (Lupin, and to the much greater degree, 
Sirius) act as if it's very important for them to pass their baggage 
with Snape to Harry? Rhetorical question, I know.

Irene