Serena really should have seen it much earlier, and the fact that she doesn't isn't entirely her fault.

Because Blair and Dan have significantly kept quiet about the amount of time they have been spending together lately.

At first Blair tells herself she's not mentioning the outings to Serena because of the shame spending so much time with someone from Brooklyn entails; later she justifies it to herself as a disinclination to be forced to admit to Serena that Dan might actually have a few redeeming qualities.

Dan tells himself that he's keeping their new-found friendship (notwithstanding Blair's denials of the term) under wraps because it's hardly Serena's business who he spends time with anymore (given that two weeks after she had supposedly 'chosen' him she moved on to the ex-con who had plotted her social destruction from his jail cell). And there really isn't anything to tell anyway, Dan justifies to himself, even though he is left with a slight niggling feeling in the pit of his stomach (guilt? anxiety? hope?).

Dan and Blair's increasing compatibility is further camouflaged from the golden-haired hurricane by the fact that both continue to banter and make digs at the other's expense. (Like most beautiful people, Serena has difficulties seeing beyond the surface of things.)

It also helps that Serena has not seen much of her best friend or erstwhile love interest, embroiled yet again in a cycle of dramas that would make Jerry Springer eat his heart out.

Although the incident with Damien had allowed Dan to come to terms with Ben's involvement in Serena's life, his rosy predictions that the rest of her friends and family would soon follow suit had not come to fruition.

It was making it difficult for Ben to adjust to her lifestyle, and was putting a strain on their relationship. Serena had tried to cajole the various people in her life to make a friend of Ben, given how badly he needed one, but so far her efforts had met with little success. Eric is still suspicious, Nate is wary, Chuck indifferent, Dan sympathetic but perpetually busy and Blair (as she had informed Serena) is trying to make connections in the business world, not the underworld.

But Serena, ever the buoyant-to-the-point-of-naivety-optimist, remains undeterred. She decides to throw a party at the loft to show off her new boyfriend.

She plans something on a smaller scale than usual, which will give Ben a real chance to get to know those closest to her, and, more importantly, for them to get to know and accept him.

She decides that a 'games night' will be a great way to force everyone to interact and have fun, no matter how resistant they are to the idea. After much wheedling, Blair and Dan promise to be there, and Nate agrees to come with his new girlfriend (Melinda? Melissa?). Chuck and Raina take a raincheck due to a conflicting business trip to Tokyo. The hardest to convince is Eric, who has remained sullen and hostile since Damien left town. But Serena plays the family card in order to mandate his attendance. Keen to do a little matchmaking and get Eric back onto what she sees as the right track, she also invites Jonathon.

Serena, like a blonder, more manic version of Robin Goodfellow, thus unwittingly sets the stage for one of the most disastrous events in their cohort's history.

Eric, already antagonistic to the night's proceedings, becomes even more belligerent when he discovers Serena has not only invited Jonathon, but that the two have been talking about him behind his back. He spends the rest of the night seemingly channelling the spirit of the dearly departed Jenny Humphrey by making bitchy comments to Ben, Serena and the deeply hurt and confused Jonathon.

Ben refuses to be buoyed by her enthusiasm, and remains stubbornly taciturn throughout the evening. (Serena's immature obliviousness to the realities of the world around her has been becoming less charming and more aggravating after seeing her naked several times.)

Melanie leaves the party in tears when a Gossip Girl blast is posted in the middle of the party that reveals Nate hasn't got over his penchant for older women, and has been sleeping with her mom.

The night is capped off when Lily arrives at the loft, having just found out that her husband had installed the man she sent to jail there behind her back, and begins screaming at Serena about her 'betrayal', and threatens to have Ben sent back to prison for continued harassment of his 'victim'. After Lily struts out, Ben also storms off.

All this almost serves to distract Serena from the fact that, out of everyone, Blair and Dan seem to be the only ones who have a good time.

They begin the night as aloofly reserved as everyone else, responding to Serena's energetic attempts to engender conversation with monosyllabic answers, seeming to draw closer together on the couch for support as the awkwardness grows.

As she tries to get Nate and Ben talking (a doomed effort since Ben knows next to nothing about lacrosse and Nate has zero interest in literature), Serena notices Blair and Dan whispering to each other in their own corner. Occasionally she hears them chuckling softly.

When she smiles and asks them what's so funny (hoping some laughter might lighten the atmosphere), Dan tells her they were just wondering if these were L'occitane washed wine glasses. When the others look confused, Blair dismisses the comment as a private joke.

Serena rallies and convinces everyone that a game of 'taboo' will be a perfect way to kick off the evening. The object of the game is to have a partner guess a name or expression without using the list of proscribed words one would normally associate with it. The team that gets the most correct guesses in a set amount of time wins.

"Okay, the game requires we play as teams so why don't we play as couples?" Serena says excitedly. When no one responds, she continues, "Okay so Ben and I will be one team, and Nate and Melissa – ooh, sorry Melanie – will be another, and Eric you can play with Jonathon. I guess that leaves Blair and Dan together." She smiled encouragingly at the pair, hoping Blair wasn't about to throw one of her tantrums about having to be teamed up with Dan Humphrey.

Instead Blair just snorts. "Well, if I'm going to be forced to play these inane games at least I have a partner with a bit of brain power," she turns and stares meaningfully at Dan, "Losing isn't something I handle well Humphrey, so you better bring your A-game."

"Relax, Waldorf. Board-game nights are a Humphrey family tradition," Dan reassured her drily. "And I just happen to be the reigning taboo champion. We've got this in the bag. Provided you don't let the side down of course."

Blair slaps his shoulder playfully in reproach. Serena shushes them so that Nate and Melanie can take the first turn.

The egg-timer is flipped on, but in three minutes the pair manages to get zero points. Nate, never the brightest bulb himself, is seriously handicapped by his vacuous partner, who spends most of her time staring at the paper and saying 'ooh, I don't know', 'ooh, that's a hard one', rather than giving him clues.

Eric and Jonathon go next. Eric makes no effort to conceal his boredom and says 'pass' frequently, but he makes a few correct guesses, putting them in the lead.

Then it is Serena and Ben's turn. Ben becomes slightly more animated as he tries to give Serena clues, but it soon turns to frustration as she repeatedly guesses wrong.

"Oh, you'll be able to guess this one," Ben says with a smile just as the timer is about to go off. "I can quote you one of my favourite passages – 'Only a man who has felt ultimate despair is capable of feeling ultimate bliss'."

"Er...I um... Shakespeare?" Serena questions weakly as the timer goes off.

"The Count of Monte Cristo," Dan says, rolling his eyes, unable to resist a chance to show off his own literary prowress.

"Personally, I prefer Dumas's more prosaic offering that it is time to 'take up the rank, influence, and power which great wealth gives in the world'," Blair quipped.

Dan makes a face. "That's not the point of the story at all and you know it," he begins bickering with her.

Serena turns to Ben with a sheepish expression as the other two continue to debate Dumas's intent.

"I haven't actually read it in a while," she admits awkwardly.

Ben gives her a tight smile, but Serena sees a familiar expression in his eyes. Disillusionment. It is a look all her boyfriends have worn at one time or another.

"Okay, our turn," Blair says officiously. "Dan, you give the clues and I'll guess."

Blair starts the timer and then turns to stare at Dan expectantly. Her posture is tense and it is clear she is eager to win.

Dan picks up the first card. He muses for a second then says, "Stars the guy whose voice creeps you out and is set in the place we always end up on Thanksgiving."

"Frankie and Johnny," Blair muses. "Although we did break with tradition this year."

"Right," Dan says proudly, taking another card. "Your Renaissance-era role model," he prompts.

"Machiavelli," Blair replies without hesitation.

By the time Blair guesses the third card right, Serena has a curious, slightly queasy feeling building in her stomach. She tries to tell herself that there is no logical reason why it should disturb her, but Dan's easy familiarity with her best friend is surprising. And unsettling.

"42," Dan tells Blair shortly as a clue to their eighth card.

Serena is sure Blair will be as bamboozled as she is by such an enigmatic hint, but after rolling her eyes Blair quickly replies, "The secret of life. I can't believe you liked that book. It wasn't nearly as funny as you and the author thought it was."

Dan's mouth quirks at the corners but he is too busy moving onto the next card to respond. His brow furrows for a minute before he says apologetically, "Nate and Duchess Beaton."

"Blackmail? Gigolo?" Blair questions hurriedly but Dan shakes his head. "Oedipal complex?"

"Yes!" Dan responds triumphantly, pulling Blair into a half-hug around the waist. The movement should be awkward, but seems surprisingly natural.

"Hey, just because she was a bit older..." Nate objects annoyed, but Dan is already moving on.

"Okay, you think his work is prurient, self-indulgent twaddle but I still think that his style of prose..."

"Oh, please, as much as I enjoy a bit of repressed male homo-eroticism, you will never be able to convince me that there is any merit in D. H. Lawrence's work unless you skip straight to the naughty bits," Blair interjects contemptuously.

Dan groans but picks up the next card.

"Most romantic spot in Manhattan," he prods.

Serena is sure that Blair will answer Tiffany's or the Empire State Building. She wonders if this one will stump the pair, because she's pretty sure that Dan thinks the most romantic place in the city is the Brooklyn Promenade or the Botanical Gardens.

But Blair catches Dan's eyes and gives him a small knowing smile. "The New York Public Library," she answers assuredly.

Dan chuckles. "One of the few things we both agree on."

He reaches for the next card, but Serena is no longer concentrating on the game. There is a sudden pounding in her ears as she wonders when exactly her ex-boyfriend became better acquainted with her best friend than she is.

While she is pondering this perplexing problem, Dan and Blair manage to rack up several more points.

They have been moving through the cards with impressive rapidity, but Dan finally reaches one that gives him pause. His face flushes, and he clears his throat a little. But his voice when he speaks is sure and steady, and filled with warm tenderness as he recites:

I'd like you even if you were malign

And had a yen for sudden homicide.

I'd let you put insecticide

Into my wine.

I'd like to find a good excuse

To call on you and find you in.

I'd like to put my hand beneath your chin,

And see you grin.

I'd like to taste your Charlotte Russe,

I'd like to feel my lips upon your skin,

I'd like to make you reproduce.

I'd like you in my confidence.

I'd like to be your only audience,

The final name in your appointment book,

Your future tense.

The timer goes off as Dan is speaking but he doesn't stop, or break eye contact from Blair.

At the end he pauses, looking into her eyes, then seems to shake himself and chuckles nervously.

"Those are the only lines I can remember," he explains sheepishly.

"Valentine," Blair says quietly, sounding a little dazed. "It's my favourite John Fuller poem."

"Well, that doesn't count. The buzzer had already gone off," Melanie objects waspishly.

Blair finally breaks eye contact with Dan to turn to the other girl.

"I think even conceding that point our total of fifteen still beats your score of zero," Blair reminds her sweetly. "And makes us the winners."

Ben and Jonathon clap for them half-heartedly. Nate is still put out that Dan and Blair have been psycho-analysing him, Eric is busy pointedly ignoring Jonathon by texting someone else and Serena is still bewildered by Dan and Blair's camaraderie and the strange moment they had both just seemed to share.

She excuses herself to the kitchen on the pretext of needing to refresh the appetizers and tries to make sense of the easy-going familiarity she had just witnessed.

"Hey S, need any help?" Blair asks, joining her in the kitchen.

"Oh, no," Serena assures her distractedly. "Go out there and enjoy the party."

Blair raises her eyebrows. "Oh yeah, it's a real riot out there," she says sardonically.

Serena's eyes narrow. "You and Dan certainly seemed to be having fun earlier," she queries uncertainly, just a touch of jealousy in her voice.

Blair shrugs non-committedly. "You know I always get a rush from beating other people," she responds lightly, swiping a piece of crudités.

"Are you sure that's all it was?" Serena returns knowingly.

Blair glares at her. "What are you getting at?"

"Well, the way you guys blew through that game it was obvious that you...well...really know each other. Plus you both just seem very...comfortable together...that's all. And I'm just wondering when exactly that happened," Serena probes acerbically.

"Well, I have known the guy now for the last four years," Blair comments drily. "And, I guess, what with the W internship, and you being busy with Ben while I no longer have Chuck and Dan no longer has Vanessa, he and I have been spending a certain amount of time together," she adds with a stab at nonchalance she doesn't quite achieve.

"But is that it? Because you could tell me if something more was going on," Serena says reassuringly. She is sincere in this. Even though the prospect of Blair and Dan being together makes her feel far from sanguine, she knows she has no right to object. And that both Blair and Dan have a right to be happy.

But Blair just gapes at her in horror. "Dan Humphrey? How can you suggest such things while I'm trying to eat? You know I have digestive problems!" she rails before flouncing out.

Serena is temporarily reassured by this discussion, as the idea of Blair and Dan together still makes little sense to her, despite their seeing connection earlier. But she supposed she could see how they might have recently become friends, having been thrown together at W. And they did share common interests.

More so than she and Ben, as this night was making abundantly clear.

When she brings the next round of appetizers out, Serena announces that the next part of the evening's entertainment is going to involve a trip into nostalgia. She's rented a karaoke machine with all sixties music.

"Can we really be nostalgic for an era none of us have lived through?" Dan questions idly.

The night however briefly starts to pick up. Serena's performance of 'You Can't Hurry Love' earns thunderous applause, and Nate's unintentionally self-mocking rendition of 'I Get Around' is like-wise well-received (though Blair, Dan and Eric can't quite hide their sniggers at the irony).

Then the GG blast hits about Nate's amorous exploits with Melanie's mum and she grabs the microphone in a fit of drunken anger and bellows out a few verses of 'Respect' before breaking off to slap Nate in the face and storm out. Nate quickly follows.

Serena tries to salvage the situation.

"Well, that was unexpected," she jokes weakly. "But we don't need to let it ruin our night. Who haven't we heard from? Eric, why don't you get up there?" she suggests with a smile in her brother's direction.

"Yeah, karaoke's not really my thing," he replies self-deprecatingly. "But Dan and Blair haven't sung yet either. And I'd bet you guys would sing a great duet," he proposes devilishly.

Blair and Dan exchange an uncomfortable glance. They both begin to protest at once.

"Oh, I don't know..." Dan starts.

"I've vowed off singing..." Blair argues.

"Please guys?" Serena interrupts, a note of desperation in her voice.

The duo exchange another speaking look.

"Fine," Blair answers for both of them.

"What should we sing?" Dan muses, reaching for the song list.

"Oh, don't worry, I know the perfect number," Eric cuts across, pushing a few buttons on the machine.

Dan and Blair reluctantly pick up the microphones as the strains of 'Daydream Believers' start to play.

Dan sings the first lines

Oh, I could hide 'neath the wings of the bluebird as she sings
The six o'clock alarm would never ring

He pokes the still silent Blair in the arm and she rolls her eyes and continues with the next lines.

But it rings and I rise wipe the sleep out of my eyes
The shavin' razor's cold, and it stings

They both join together for the chorus.

Cheer up, sleepy Jean, oh what can it mean
To a
(Blair motions to Dan) daydream believer and a (Dan looks at Blair significantly) homecoming queen?

Having got into the song, Dan and Blair grin at each other and being to sway to the music as they sing the next verse.

You once thought of me as a white knight on his steed
Now you know how happy we can be
Oh, and our good times start and end without dollar one to spend
But how much baby do we really need?

Serena is once again transfixed by the sight of them together. And she is finally able to put her finger on it. They already look like a couple!

But this realisation is interrupted by the untimely arrival of Lily, which cuts short the duet and the rest of the evening.

After Ben has stormed out, and Eric and Jonathon have said their separate goodbyes, there is only Blair, Dan and Serena left.

"Don't worry S," Blair comforts a tearful Serena. "He won't be able to stay mad at you. They never are." (This sly dig at his own – and every other male's – gullibility when it comes to Serena Van der Woodsen earns a quick smile from Dan; unseen by Serena of course.)

"He'll be back here before you know it," Blair continues soothingly.

Serena nods her head shakily. "I hope you're right," she sniffs. "I think I'll wait here for him."

"Do you want me to stay with you?" Blair asks sympathetically.

Serena smiles waterily. "No, it's fine. You should head back to the penthouse."

"Okay S," Blair gives her hand a final squeeze before going to collect her scarf and coat.

"I'll see you outside in a minute," Dan calls after her.

"It will be alright," Dan tells Serena, turning back.

"Actually, I don't know if it will," Serena shakes her head sadly.

"I think maybe I made a mistake. I fell in love with the idea of this man I knew five years ago. But I don't know if that man still exists, or if he ever existed outside my schoolgirl fantasies. Maybe I just wanted to be with Ben because of what he represents," she goes on.

"A chance to break away from my world, from my mother...Or maybe I just used him as an excuse because I was afraid to face the future. To go after what my heart really wants," she looks at him meaningfully.

"Serena," Dan sighs. It is a slightly exasperated sound and Serena cuts in.

"Will you wait with me here tonight?" she pleads. "I could really use the company," she smiles coaxingly.

Dan hesitates for a second, then turns and looks towards the door.

"I've got to see Blair home. Make sure she gets there safely," Dan tells her definitely. "What you really need is some time for self-reflection, and then the chance to have a heart-to-heart with Ben without anyone around...I won't come back tonight, so you two can have some privacy."

And while this all sounds perfectly reasonable, Serena knows in that second what is really going on.

Dan has chosen Blair over her.

He may not know it yet, but Serena has lost him forever.