Blood Pact

Angelus would be interested (i.e. Laz is interested xD). He's very green and very naive, but once someone has his respect his loyalty is unwavering. The best way (but not necessarily the only way) to get his respect would be to thoroughly trounce him in their first meeting. If Angel was made to understand that he could better himself if he followed Sin then he'd jump at the opportunity. He'd have to be trained, however, as no one in his old pack bothered to teach him anything. The instincts are there, they just need to be molded.