Angel hasn't cast binding spells before, but he's assisted in setting them up more times than he can count. Those spells involved binding a person to a plane or an object, not a person to a person, but it was the same principal. He'd done something similar recently with the talisman that the vampire glamour perpetuating his still undead lie was bound to. The spell to it and it to him.

He just had to modify it to be person-to-person. That wouldn't be too hard. Tricky and difficult, maybe, but not impossible. And not any less complicated than the primordial magicks he's been dabbling in for months.

"Your blood."