Looking at the film through the lens of sexuality reveals what appears at first to be a fundamental binary of the movie: Hetero-Heros vs. Homo-Villains.
Let's start with the negative, the Other who negatively defines the Self of the Heroes & Audience. This reading notes the particular ways in which Loki is sexualized, often minor or tangential but still grossly stereotypical.
His posh English Accent -- with something of a lilt on the high tenor end -- often sounds effete to American ears (and probably many British ears too). He has long dark hair -- stylized hair. He wears elaborate, fashionable outfits. Hates and envies his Jock Older Brother: Thor, (Heterosexual) God of Thunder. He has unresolved Oedipal issues with his one-eyed adoptive father: Odin, King of the Gods and All-Father. Loki's not really one of the Asgardians (would Ass-Guardian be TOO obvious?), but a Frost Giant -- are there Frost Giant women? -- so he seems to be the product of a mono-sexual masculinity. His chief weapon is a (phallic) spear given to him by a mysterious alien power which he uses to figuratively steal the hearts of men -- at least, his army of mind-slaves appears to be exclusively male (correct me if there were females in Loki's human army, certainly the main 2 were male: Hawkeye/Barton & Selvig). But, the transmission of his power is through contact, and seems to be a sort of infection of the mind, as well as a rape of it (cf. Hawkeye's description upon recovery). He wants to invade and enslave all of humankind, whom he commands to get "on [their] knees!" before him.
Loki is backed by an army of unisex lizard aliens. Led by a mysterious "Him," who is revealed post-credits (to those in the know) to be Thanos, the Marvel cosmic supervillain personification of Death (from Thanatos, the Greek daemon of death and Freud's term for the "death drive," associated by Lee Edelman with homosexuality, blah blah blah). Loki wants to open a secret dark hole to let in the invading aliens and their giant evil flying sperm whales.
On the other side, the heterosexual powerhouse of the Avengers Men (and super-hot Chick). I think that it is fairly obvious that in comparison to Loki the Avengers are explicitly heterosexual -- or rather, their sexuality is mostly invisible, normal, normative, only a small part of their character when visible. It is presumed and not referenced in the same way that Loki's sexuality is somewhat more explicitly displayed.
But, in case it is not obvious, here's a very brief summary of the markers of heterosexuality of Our Heroes:
Tony Stark/Iron Man: Notable Playboy, now with Sexy Serious Girlfriend. Tony Stark's girlfriend appears more than any other non-hero female in the film. Scantily clad, also his personal assistant/mother/ego massager. And he says to Captain America that he's a billionaire playboy. So, he's super-hetero.
Thor: Super macho dude, in love with Natalie Portman (seen on a computer screen to remind us), plus that Sif warrior-woman clearly has the hots for him too.
Bruce Banner/Hulk: Betty Ross (Liv Tyler/Jennifer Connolly) is his tragic lost love from previous films. Mostly de-sexed here as Mark Ruffalo plays the Woody Allen version of Bruce Banner.
Steve Rogers/Captain America: A man out of time, we are briefly reminded in a flashback of his lost love from WW2, who aged and died while he was frozen. Also mostly de-sexed except for two exceptions: one VERY notable, discussed later; the other the star-struck Waitress in an Old-Timey Diner outfit whom he saves, and who later talks about him on the news.
Natasha Romanov/Black Widow: Super-sexy Super Spy, damaged but deadly, with some sort of bond to Hawkeye, whom she fights with while fighting to win him back from the All-Male Loki Army.
Nick Fury: The father figure. Like Odin, missing an eye. Old enough, gruff enough that his patriarchal authority need not prove its sexuality. It is assumed. Still, while he isn't sexualized, he does have a super hot female assistant, loyal to the death.
But then I realize, the heterosexuality of the heroes is actually far more explicit than the homosexuality of the villain. That is to say, the homosexuality of Loki is secondary, it is implied by tired stereotypes, never explicitly stated. The sexuality of the other characters, in so far as they are sexual at all, is heterosexual and at least a bit explicit. This assertion of heroic heterosexuality against vaguely effete unreproductive anality seems a bit anxious -- the lady doth protest too much, methinks syndrome.
Next time: A few notes on the finer points of the characters and their relationships.
