[He grimaces.] I went out for a walk in the park after dark and took a tumble over a tree root or something. Gashed my hand rather badly and it wouldn't stop bleeding, and Spike just happened to be around to smell it.
[At least, he's always assumed Spike just happened to be around. He didn't seem to be stalking him at that point.]
So he started to tease me about it but I really wasn't in the mood. I mean, yeah, once upon a time I'd been intrigued by the idea of how hot it might be to get bitten, but that was before Ianto and I got blue-banded. [And before he'd got bitten by Rebekah in retribution for trying to conceal his relationship with Ianto from her] I tried to tell him to shove off but he wasn't having any of it and it actually got a little unsettling. He was out for blood - literally - and in the end he just went for it. Vamped out and knocked me down and - after a bit more taunting - bit me.