Quoting *B & D Mommy*:" And I'm confused about the sire thing...because he told her to do a few other things before he told her ... [snip!] ... told her to turn off her "switch" and she didn't listen until then. So does the sire bond only work for certain things? Lol "
I think it was because he told her it was what he wanted her to do... That it would make him happy if she turned it off. I know when the sire bond was explained by Tyler he said that he still hates Klaus but he had to do everything Klaus wanted him to do but when it was explained for Elena and Damon it was basically said that he has to tell her that it will make him happy if she does it.
I don't know though cause that confused me last night too.