User blog comment:FairyRaven/Fairy Tail Chapter 368: The Third Seal, Review and Commentary/@comment-2074153-20140125171414

I don't think Cana questioning Elfman returning without Lisanna has anything to do with how smart she is. More likely, it has everything to do with guilt, over the fact that Cana herself abandoned Lucy during the Tenrou Island arc, and for far less solid reasons. Namely, to pass an S-Class exam that had already been canceled. Mind you, I still think that Cana was supremely out of character during that arc, so I personally found it rather ironic that she would be the one to question Elfman for that very reason. Natsu would have been more fitting, given his relationship to Lisanna and his confrontational nature. He likely would have punched Elfman in the face, which possibly could have revealed that Elfman was under someone's control, or knocked the lacrima out of his pocket. Cana being the one means some people might just pass it off as her usual drunken shouting. Notice how pretty much no one backs her up. I doubt that would have happened with anyone else confronting Elfman.