Just a one-shot about how Nate should have known what was going on between Chuck and Blair.

The truth is Nate could have known that it would be Chuck and Blair from the beginning, if he'd just paid attention to the ring tones on his best friend's cell phone.

Chuck had always prided himself on choosing ring tones perfectly suited to the personalities of his callers. Bart's phone calls had always been heralded by the forbidding tones of Beethoven. Serena, despite the blonde's high-pitched and outraged objections, had long been designated Aqua's 'Barbie Girl' as her call signal. And Nate had guffawed over Chuck's choice of 'Because I Got High' by Afroman for his best friend.

Way back when Chuck had got his first cell phone (the only second grader to then have one) he had made 'Bitch' by Meredith Brooks the ring tone for Blair Waldorf's calls. Blair was at first offended by the sarcastic selection, wielding her Prada purse into the side of Chuck's head with all the strength her seven-year-old frame would allow. But Chuck had explained that he meant the choice of ringer as a compliment; he considered Blair Waldorf the only person he knew that could out-bitch himself. Huffing, Blair had greeted this strange form of flattery with a mollified smirk – smirking was another area in which Blair could rival Chuck Bass. From then on the tune became something of a theme song for Blair throughout grade school.

But during sophomore year Chuck had given Blair a new ring tone, the Black Eyed Peas' song 'My Humps'. At the time Nate had been somewhat distracted by the mysterious disappearance of a certain blonde and the event he believed had triggered it, but Blair was still technically his girlfriend (however much he had been avoiding her) and he felt constrained upon to comment upon the suggestiveness of the new ringer's lyrics.

Chuck had explained that he thought the switch appropriate, given the way Blair had recently grown into the curves that had been promising to develop since puberty.

His mind occupied only with thoughts of Serena (whose figure had been fully formed since the age of twelve) Nate had failed to notice the way Blair's body had lately grown more lush and womanly. But it seemed his best friend had been more observant.

"You shouldn't talk about her that way, Chuck. She's my girlfriend," Nate protested, although his heart wasn't fully in the objection.

Chuck had raised his eyebrows. "So I'm supposed to be blind to how effing hot she's become just because she's your girlfriend? Not possible, Archibald."

Nate shrugged his shoulders apathetically.

Chuck's eyes narrowed. "The song's totally appropriate, Nathaniel. Blair's the type of girl any guy would be willing to 'spend time and money on'. You want to be careful if you're planning on still being the one to tap that ass."

Nate had straightened up, afraid that Chuck might guess the cause of his recent indifference, not knowing that Chuck knew the exact origins of his ennui due to the floor show he had witnessed at the Sheppard wedding. Hence the attempt to give Nate a subtle warning about what he potentially risked losing by his vacillating affections.

Chuck's comments had inspired Nate to pay more attention to Blair again, at least until Serena's return.

After Serena came back and Blair had eventually forgiven them both, all four had gone out to celebrate one evening. Upon reaching a karaoke bar Chuck had dared Blair to get up and sing 'My Humps' on stage. Never one to back down from a challenge Blair had accepted, stipulating only that Chuck provide the male vocals. The two had given an exaggeratedly sexy performance together, Blair showing off her dancing talents by shaking her 'humps', incidentally fulfilling one of the leering boy's secret fantasies. But Nate had missed the intense looks Chuck gave Blair as she moved around him, his own eyes intent upon the golden-haired goddess at his side.

After Nate and Blair broke up, Chuck had once again adjusted Blair's ringer, this time to Shaggy's 'Luv Me, Luv Me'. The song could have told him everything he needed to know about the change in Chuck and Blair's relationship that had taken place that night at Victrola, but at that stage Nate was too distracted by the multitude of dramas in his life (his father's arrest and subsequent overdose, his mother's unhelpful denial, his break-up with Blair) to really take note. When he did become aware of the raunchy lyrics that were now signalling calls from his ex-girlfriend to his best friend (which had strangely increased in number), he merely sighed and figured it was some attempt to rile Blair up by associating her with the hip hop number's lewd suggestions.

Blair had thought with a disgusted sigh that the new ringtone was simply a sign of Chuck's insane egotism that he had to subtly proclaim that he was 'da man' that the virgin queen of Constance allowed to make her 'moan and sweat' and 'scream out yes'. Nate never guessed that Chuck had chosen it because he not only actually found Blair 'sweet, succulent and fine' but really did consider her 'to be the type for me to wine and dine, a little candlelight dinner toasted over some wine'. She was the only girl he had ever wanted to do such things with, the only one who he had determined from the first deserved to be treated with all the considerations of a real lady, whether that meant buying her diamonds or proving that he could be the perfect gentleman, perfect date.

(Serena told Nate later, much to his annoyance, that Chuck had also changed his ringtone during this period to 'My Girl's Ex-Boyfriend' in a sardonic expression of his gratitude for Nate's idiocy in breaking up with Blair in the first place. Chuck had been careful to see Nate didn't discover this, of course.)

Then, during Nate and Blair's brief reunion, the strains of Marilyn Manson's 'Tainted Love' had become the harbinger of a call from Blair. When Nate had queried this choice, Chuck had told him that it was in honour of Nate's recent de-virgining of Blair. She was now tainted, Chuck had said with a smirk. Nathaniel had not noticed the flicker of pain behind it. He had just rolled his eyes at his friend's cynicism and complete lack of any sense of romance.

But of course the song was actually a perfect fit for how Chuck felt about Blair, the strange sadistic games they played together. Nate's only inclusion in the song's referential qualities was that he was part of the source of 'the pain driven into the heart of me' Chuck experienced after the end of his brief affair with the petite brunette. The reason he had felt the need to 'run away'.

Then Chuck had sent the notorious blast to Gossip Girl and Nate had discovered their double betrayal and all their worlds had come crumbling down. In the months that followed, when he was speaking to neither Chuck nor Blair, Nate had obsessively gone over their interactions in his head, searching for the clues he could have missed that might have warned him of the treachery of the two people in the world who he considered his closest friends. It was then the significance of Chuck's ring tones had occurred to him, and he had berated himself for his blindness and his foolish faith in his best friend's infamously suspect integrity.

This new-found knowledge had made him all the more curious when he eventually heard Chuck's new ringtone for Blair. She had called him on the day she was out searching for Serena, ringing to inform them both as they waited uneasily in her foyer that she would be there ASAP. Nate had been unfamiliar with the song that emanated from Chuck's phone to signal Blair's call. However, he had been too mad at Chuck to break the silence to inquire what it was.

But later he hummed the lines to Vanessa and she informed him that it was Billy Joel's 'She's Always A Woman'. Chuck's musical tastes had always been more eclectic than Nate's, who mostly preferred anything in the pop rock line that had come out from 1998 and onwards. Chuck's CD collection however ranged from classical and operatic compilations to bluesy jazz and 1980s rock ballads. But Nate had been inspired to google the song when he returned home that night, even going so far as to print off the lyrics.

She can kill with a smile
She can wound with her eyes
She can ruin your faith with her casual lies
And she only reveals what she wants you to see
She hides like a child,
But she's always a woman to me

She can lead you to love
She can take you or leave you
She can ask for the truth
But she'll never believe you
And she'll take what you give her, as long as it's free
Yeah, she steals like a thief
But she's always a woman to me

Oh--she takes care of herself
She can wait if she wants
She's ahead of her time
Oh--and she never gives out
And she never gives in
She just changes her mind

And she'll promise you more
Than the Garden of Eden
Then she'll carelessly cut you
And laugh while you're bleedin'
But she'll bring out the best
And the worst you can be
Blame it all on yourself
Cause she's always a woman to me

Nate had never heard a song that suited Blair's personality more. It made him realise the Chuck undoubtedly had a better understanding of Blair than he or Serena did, probably even knew her better than she knew herself. It was this realisation that inspired him to believe Chuck when he told him at the wedding the next day that he loved Blair. It helped him to finally let go of his anger over a relationship which, if he had been paying attention, he really would have seen was inevitable.

During the brief week between the wedding and Chuck and Blair's projected trip to Tuscany he hadn't seen his recently-reunited-with best friend that much. On the one occasion Nate had been able to briefly lure Chuck from Blair's company he had discovered that her incessant ringing was now flippantly portended by Sinatra's 'Come Fly With Me', a light-hearted reference to their upcoming vacation together. Despite the small tug of remorse Nate still felt when he thought of Blair, he couldn't help but smile when he heard the ringer and the bright future his friends' had together that it seemingly symbolized.

Nate had been flabbergasted when he heard that Chuck had not boarded the plane for Tuscany. He had raced round to his rooms, intent on giving the other boy a piece of his mind and maybe a good poke in the eye for leading Blair on again. He had frozen at the sight of Chuck sitting in the darkened bedroom, totally dejected, two-days' worth of growth shadowing his jaw line, one hand nursing a glass of scotch. His other fist was curled tightly around his cell phone, which was emitting the tune 'She's So High' at regular intervals as Blair tried vainly to contact him. Chuck didn't have to explain about his conversation with Bart for Nate to understand what the problem was. Chuck had decided that Blair was too good for him, that she was out of his reach, and that he was a fool for ever thinking otherwise. In his mind Blair was perfect, was 'Cleopatra, Joan of Arc or Aphrodite' and he had nothing to offer the high society beauty. He knew where he belonged so nothing was going to happen. And he had chosen a ring tone that would constantly remind him of that fact every time he was tempted to answer one of her calls and beg forgiveness.

But Blair's return, and the sight of her with another man, had changed Chuck's mind. And as he embarked on his protracted game of cat-and-mouse with Blair, one always advancing while the other fell back, only to have a sudden reversal in positions between them, Chuck's cell had of course reflected this spiritedly shifting dynamic. Serena and Nate had both giggled the first time they heard Kate Perry's 'Hot n Cold' coming from Chuck's phone. It was outrageously fitting for the duo. When she had heard it Blair had naturally retaliated by setting her ringer for Chuck to the Pussycat Dolls' version of 'Perhaps, Perhaps, Perhaps'.

But after the insanity of father's funeral and Chuck's ensuing disappearance Chuck and Blair's relationship had once again shifted. As Blair fought for Chuck, supporting him as he waited for the lawyers to sort through his father's papers and call a meeting for the reading of the will, he had allocated her a song with sweeter strains. Evan and Jaron's 'Crazy For This Girl' seemed to reflect the intense feelings Blair brought out in Chuck, the gratitude he felt towards her, even though he repeatedly failed to translate those emotions into words. Perhaps Blair might have held on longer if Nate had revealed to her the strange secrets disclosed by Chuck's calls, or the new melody he had given to hers.

Nate did not know what the ringer for Blair was following the catastrophic brunch and what Chuck would only refer to as the 'elevator incident'. Blair, having announced she was done, never called Chuck anymore. Nate knew though that Chuck often wished she would, given the amount of time he tended to spend staring at his cell phone.

Nate had been afraid to hear what song would indicate Blair's calls after he had broken up with Vanessa and sought stability with his childhood sweetheart. An angry rock anthem about the fickleness of her affections? A depressing emo ode to how they had both effectively ripped his heart out once more? Or crudely suggestive hip-hop lyrics that would make Nate wonder if things really were over between his girlfriend and best friend, of if he was once more missing the nuances of their interactions, which were never without passion or meaning?

He had eventually heard the ringer on the day he showed Chuck his new apartment in Murray Hill and Blair had called to scheme about exposing Serena's shady southerner. To Nate's surprise it had just been a standard ringing tone. It was the first time he had known Chuck not to assign a personalised song to a caller. Nate tried to convince himself that Chuck had allotted Blair the non-descript noise because she was no longer of much importance to him, but deep down he knew the truth. Chuck's feelings for Blair were now much too painful, too private, to be bared before the world.

Nate should have known then. He should have known that it was only a matter of time before Chuck worked up the courage to admit to Blair that he loved her. And that once he had got that first 'I love you' off his chest, he'd keep repeating it to Blair over and over again, conceivably for the rest of their days.

Nate had told all this to Blair eventually. She had just given him that knowing Blair Waldorf smirk, the same one she'd bestowed on Chuck in grade school. And Nate had asked her, curiously, if she knew what Chuck's ring tone for her was now. She nodded, smile growing wider, as she told him it was Constantine Maroulis' 'Girl Like You'. And as he watched Chuck hold the newly named Mrs Blair Bass in his arms, Nate knew it was another perfect fit. The girl was his moon and sun. He had been waiting for her all his life, and now she was here to stay.

Hey, didn't want to include all they lyrics to all the songs here but felt I should include Billy Joel's cos to me they are so perfect for Blair but I wasn't sure how many people would know them. I guess most of the rest are pretty familiar or can always be googled anyway. Also there are great Chuck and Blair music vids for 'Bitch', 'Tainted Love', 'My Girl's Ex Boyfriend', 'She's So High', 'Hot n Cold', 'Crazy For This Girl' and 'Girl Like You' on youtube.