His first year with SHIELD Clint didn’t bother celebrating his birthday. He was ten days into a stakeout in the former Czechoslovakia, it was pissing down rain, and by the time they called him down from his perch he’d managed to pick up a moderately severe case of pneumonia. After that he was transferred to a new handler. The man had a bland, average face and a pleasant voice. He introduced himself as Agent Coulson, he shook Clint’s hand and looked him in the eye.
Years two through four passed mostly quietly. He went on missions. He killed targets. He provided support for countless operations. He made a reputation for himself among the other agents.
Clint worked with seventeen separate handlers before someone higher up finally bumped him back to Coulson. Like before, Agent Coulson shook his hand; this time, he smiled wryly and said:
“Agent Barton, a pleasure to see you again.”
“Apparently, I’m difficult to work with. I guess we’re stuck with each other.”
Clint gave him a disbelieving look. Coulson shrugged, self-deprecating. It took an embarrassingly long time for Clint to figure out it wasn’t that other people found Coulson difficult to work with, just disconcerting. Coulson was his last handler.
The birthday of his fifth year he spent in a grimy hotel in Budapest with a bullet wound and a bottle of vodka. Natasha seemed to think these made excellent gifts. Clint was starting to wonder if somewhere along the way he’d managed to set a very bad sort of precedent.
For the first time in five years, Clint wasn’t working on his birthday. Natasha was stateside too. She wrangled together another bottle of vodka and and off duty Coulson. They cooked dinner in Clint’s tiny, understocked apartment kitchen and ate off his chipped, mismatched plates. He never knew Coulson was such a deft hand at French omelettes (apparently his mother had loved watching Julia Child's cooking show).
They got a little drunk and Coulson laughingly told him to call him Phil and Natasha kissed him on the mouth, just a little, and they watched all of the Indiana Jones movies-- or technically, just the first three because they all none of them will acknowledge the existence of the fourth.
Clint went to bed full and bleary and warm. He was 29 years old and he didn’t really know what family was supposed to feel like, but he imagined it might be something like this.
On his 30th birthday, Natasha railroaded him into a nice suit from halfway around the world, via cellphone. Phil took him out to dinner at a tiny, hole in the wall Japanese place. That year Clint had discovered a heretofore unknown addiction to sushi.
In an obvious fit of daring, Phil slid his hand across the table, an offer. Clint touched their fingers together, tip to tip, and afterwards they took a taxi back to Phil’s tiny, well kept apartment. Clint had spent a lot of time there in the last few months, bumming home cooked meals and being educated on the finer points of reality television (trying somewhat fruitlessly to share the brilliance that was Farscape in return).
Phil kissed him quietly and took him to bed.
When she got back from assignment, Natasha gave him a smirk.
His eighth year with SHIELD, he spent his birthday clearing rubble out of their--his--apartment (Phil had put his name on the title at some point, though he’d never had time to mention it; Clint only found out when they read the will).
There was no food or smiles or friends or family. Natasha might have done something but he’d taken to avoiding her. For the time being, she let him do it (Stark, or more likely Pepper, made a few comments about celebrating his birthday, throwing an Avengers party maybe but Natasha had squashed those plans as well, she knew, better than anyone how little he would have appreciated it).