As previously announced, Thor's Lady Sif (Jaimie Alexander) will pop up in an upcoming episode of S.H.I.E.L.D. and now we finally know why! "She's here to hunt down another Marvel character," executive producer Jeph Loeb said of Marvel villain Lorelei (Elena Satine, who played Mera on Smallville). "Lorelei is from Asgard. She's a beautiful redhead who has the ability to sway men's minds. She has this in her own unique way of speaking."