Thank you - I didn't want to be the one to bring that up. I was thinking today about "I'm nothing like Angel" and I thought "Yeah...you are". Then it occurred to me - we know about Spike's relationship with his mum (which I can tie to Slayer etc) but not Angel's. Angel's special relationship was with his sister. Spike's thing is Slayers - Angelus thing was nuns (I'd translated this to Mother Superior but Sisters makes more sense). It would make sense as to why Spike's extra protective of Dawn (other than the "little bit" reference). I was watching the episode where he knocks the Hellion off his bike - Spike really want to join them - Says to Dawn "It looks fun" - then puts his hand on her shoulder. I thought - he's not doing this just for Buffy. Wasn't Angel attracted to Buffy's purity? It makes sense that Angelus would want to do the opposite. Plus - Spike channels Riley in the "You're the One" speech.I'm not sure it does fit, especially when he talks about damaging his victims just enough to make them cry. That does sound more like Angelus than the fists and fur flying Spike.
The remark you make about about Andrew being "spikised" - I think they're twinned at points - Buffy say Andrew take on flavours like a mushroom. Wondered if Spike was doing the same. He definitely channels Angel in After the Fall.