OOP: MWPP and their houses/Tonks' purpose

[outahand6789]

No: HPFGUIDX 64828

Although I always imagined them all in Gryffindor, if forced to 
divide MWPP into different houses I'd say:
James:  Gryffindor  
Sirius:  Slytherin
Remus:  Ravenclaw
Peter:  Hufflepuff

This is where the sorting hat's new song (p.200-something in OP) 
would shed some light.  They could have spent a significant amount of 
time together regardless of being in different houses because they 
don't seem like the type to stay in their respective commonrooms.

James was definitely a Gryffindor, I'm pretty sure that's been 
written somewhere.  Remus shows great intellect, if not Gryffindor, 
definitely Ravenclaw material.  Peter would have never been sorted 
into Gryffindor because he's a coward (the sorting hat makes it clear 
that only those with courage go Gryffindor and the hat would have 
seen right through him) so if Sirius goes to Slythierin, then Peter's 
stuck in Hufflepuff. ***does anyone else get the feeling that 
Hufflepuff's full of rejects?***

Sirius is very interesting.  I agree with you that his family ties 
may have landed him in Slytherin.  Perhaps it was the consequences of 
joke he played on Snape (PoA p.357) that made Sirius and James mature 
sometime after their fifth year.  Something pretty big must have 
happened to make them change from being as arrogant as in Snape's 
memory from OP.  This change may be what made Sirius leave his 
house.  I hope we'll get more of that story in the 6th and 7th 
books.  I really like Sirius, his death just felt so pointless it 
still hurts.