Here is another outside-the-box idea for an Alice Krige casting: I had noticed on one of my viewings of The Avengers that Selvig was going around talking about the Tesseract in anthropomorphic terms ("She's an energy source. If we turn off the power, she turns it back on.") At the time I figured that was evidence of Selvig being in danger of losing touch with reality. Later, I was reading up on the Cosmic Cube on the Marvel web site, and it turns out that they can eventually become sentient. So maybe Krige is the personification of the Tesseract and has ways of interacting with people's minds.