Thanks for the recommendation. Buffy would be a good bodyguard against Immortals. She has superpowers and a lot of experience with fighting and beheading. Even if the Immortal managed to hire enough firepower and manpower to take her down, she's connected to a lot of people who'd be quite willing and able to hunt down and kill the Immortal involved. I suppose that other good candidates would be someone from the Justice League or an X-man. Wolverine would be ideal. However, I suspect that the other X-Men and the members of the Justice League would simply try to send the Immortal to jail. (I haven't actually read any comics for these series so I could be wrong.) That wouldn't be as much of a discouragement, as it seems that supervillains are always escaping from prison.