User blog comment:TheLastLastDragonlord/Sacrifice?/@comment-4814726-20120604015245

Ifit's about balance, then I think the sacrifice would need to be human. Not only that, but someone close to Merlin since Arthur was his best friend. I think that's why Igraine died for Arthur rather then some unknown peasant or something. If Uther was given someone important to him than someone else equally important had to be taken. Like in that one Smallville episode where the main guys GF dies and he bargains with some entity for her to live. So instead of his GF dying his dad died.