So sapphirescribe mentioned that she might want to try reading some Clint/Coulson to which I promptly clubbed her over the head and dragged her into the fandom. I've put together a little primer to help ease the way.
This is Phil Coulson:
Phil Coulson has the distinction of being of being one of the few recurring characters created for the Marvel cinematic universe. His first appearance was in Iron Man followed by Iron Man 2 before his role was significantly expanded for Thor and The Avengers. He was the lead in two short film DVD extras and has had his character written into the comic book universe. And now, of course, Coulson is the main character in Joss Whedon's newest series, Marvel Agents of S.H.I.E.L.D. But forget all that. What you really need to know is that Phil Coulson is the coolest of the cool, unassuming and measured, he meets challenges from pouty superheroes to world level threats with the same enigmatic half smile and supreme competence. Unless you mess with his Captain America trading cards. Don't mess with his trading cards.
Clint Barton, aka Hawkeye, aka omghisarmshowaretheyreal:
According to comic lore, Clint Barton was the youngest child of an abusive, alcoholic father who killed himself and Clint's mother in a car accident leaving Clint and his brother Barney orphaned and wards of the State. After a few years with social services, the Barton brothers ran away to join the circus. Clint was mentored by The Swordsman and then Trick-Shot, neither of whom were good people, and subsequently abandoned to his fate by Barney and Trick-Shot who had become partners in crime. This is the point where canon and fandom diverge but general consensus in fanon is that Clint joins SHIELD, acquires Coulson as a handler, then Natasha as his partner. Clint and Coulson share about 2 minutes of screen time in Thor, so obviously they're soulmates and destined to be together.
Natasha Romanoff, aka Black Widow:
Natasha Romanoff is SHIELD's premiere super-ninja-spy-assassin and Clint's partner and BFF. Independently they're deadly. Together they could burn the world down. Coulson is generally portrayed as their handler and the stabilizing influence necessary to make their little troika work. Fanon tends to have them relating on a level of codependence that is, frankly, a bit terrifying but also completely and totally awesome! Natasha's backstory has her portrayed as the most functional product of a Russian Super Soldier program that obtained her as a child and conditioned her into a deadly assassin. Eventually she went rogue until crossing paths with Clint, who pulled her into SHIELD.
Nick Fury:
Supreme leader and resident badass. Enough said.
Maria Hill:
Maria Hill is Fury's second in military operations. She is dedicated, loyal and extremely proficient. It's not entirely clear where she and Coulson fall in SHIELD hierarchy, who takes precedence over who, but the appear to be each others counterparts, with Maria relying on a more procedural military background and Phil favouring a flexible attitude in getting results.
Jasper Sitwell:
Jasper Sitwell first appears in Thor as Coulson's second in command. He makes a brief appearance in The Avengers and is billed to play some kind of supporting role in Thor 2. Additionally, he appears alongside Coulson in the short DVD extra feature "The Consultant". Sitwell shows up in a large number of SHIELD fic, to deliver snark and generally being awesome.
Darcy Lewis:
Like Coulson, Darcy Lewis is an original character to the Marvel movie universe. She first appears in Thor as Jane Foster's assistant (Jane is Thor's physicist girlfriend), where she tazes Thor, introduces him to coffee, creates a fake id for him, and assists in causing some minor mayhem, frustrating Coulson and endearing her forever to the fandom. The fandom loves her and she often shows up in fic as Coulson's assistant/minion post Avengers. She's sassy and snarky and blatantly ogles superheroes. She is us.
Why I love them:
I have a kink for competent men a mile wide and these two fit the bill. Coulson's background is wide open to interpretation which makes for some fun origin stories, and Clint's background lends itself well to emotional complexities that the fandom authors exploit beautifully. Add to that the nature of their profession and you get some beautiful hurt/comfort of the "hard men being soft" variety that I am crazy for. Honestly, what's not to love?
Fic Recs Short Films
A Funny Thing Happened on the Way to Thor's Hammer <--immediately precedes Thor and showcases "Coulson's complete BAMFery.
The Consultant <--post Thor and pre Avengers, works to tie The Incredible Hulk into Marvel's Phase One.