Based on the Asgardian war goddess devised by comic book creators Jack Kirby and Stan Lee, Lady Sif emerged from 2011's Thor motion picture as something of a breakout character, with fans complaining that the charismatic performer Jamie Alexander didn't get enough screen time and asking that she star in a spinoff of her own. Marvel Studios seems to have listened, with early reports indicating the character's role has been beefed up in the sequel, Thor: The Dark World. In addition to her typical ass-kicking duties, Sif will supposedly become a romantic rival to whoever that earthling doctor or whatever Natalie Portman plays is. Obviously Lady Sif could win any sort of contest under literally any circumstance, so it's safe to assume Portman's character will just, like, go back to wherever they hid her in Avengers and let the third movie be about Sif and Thor punching astro-orcs and making out as space lighting crashes romantically in the distance.