Maybe, maybe not, Sirius was not in favour with the Dark Lord and Regulas may turn out to be a small hero as well..
*Snow looks at Mrs Luca Black and chirps happily*
It has been talked about on here - I think DD wanted Slughorn at Hogwarts for a couple of reasons
1) so that he could watch his behaviour
2) to get a memory from him - he always suspected didn't he
3) so that Harry could meet him and actually get some decent potions lessons in - I think this play an important part later
4) to give Slughorn protection for a bit while all the above happened
Do we think that Slughorn would really stick around at Hogwarts even if it does stay open next year? He'll be a coward on the run I reckon as he only felt safe in Hogwarts knowing that DE's couldn't get in, well that's not the case anymore and that DD was around as a protector, well that's not the case any more either...