Old Question (probably already answered) about Black and wands

[huntergreen_3]

No: HPFGUIDX 113001

macfotuk wrote:
>>Are there any theories out there I haven't seen about why Sirius
laughed? [snip]
Could Pettigrew have hexed Sirius just before blasting a hole into
the sewer by which he escaped as scabbers? (I don't recall a mad
laughter spell), but there is a mad/uncontrollable dancing
(tarantallegra) spell after all.<<

HunterGreen:
I think it was a cheering charm. Notice how earlier in PoA cheering 
charms are mentioned several times (first in class when they learn 
it, then when Hermione is horrified that she missed that lesson, and 
I think they show up in the exam too), but never again. I sort of 
wonder if JKR almost intended to slip in that Peter used a STRONG 
cheering charm on Sirius to make him appear insane, but it didn't 
make it into the text. It is interesting that we learn about cheering 
charms in the same book as all the Sirius/Peter stuff.

It could be though, that Sirius was just having a stress-induced 
laughing fit, meaning that he was a little insane at that moment 
(after having his two best friends killed, then being framed for 
murder and watching 12 people die and someone else chop off their 
finger, I can imagine he was a little emotionally charged). I wonder 
though, have we seen Sirius react that way (or similarily) other 
times he's been upset?