Hey there I'm Lucy! ANd I have to girlies, first is Ginny Weasley, who obviously likes very much Sirius not only cos he knew him back in the future(I always wanted to say that XD) but also cos his personality goes with her, She is very smart and radical on her views, and well pretty canon really, just not that into Harry anymore. I was thinking it would be a funny line if Ginny liked Sirius a bit too much, if yah know what I mean.
Ginny likes Lisa on general grounds, she has a thing for logic on some occasions, but she is also overly dreamy, likes to think of 6 impossible things before breakfast!
Now Crisis or Orcaphilia Lovegood, is a little bad ass punk with a nerve for breaking down stuff, pulling pranks and being very loud and obnoxious, my guess is that she and Sirius will be very good mates.
Now I'm sure Crisis and Lisa clash a lot and have their fair amount of trouble, since Crisis wants caos.