"For me, the benefit is that even though we're doing the things we used to do: eating pirogies and going to see Ugetsu for the sixth time... now I get to do them with you as my girlfriend. Which is why just sitting here with you is the most romantic date I could imagine."
-Dan to Vanessa, The Empire Strikes Jack
Dan and Vanessa have been best friends since childhood. When they were 16, Dan told Vanessa he loved her as more than a friend but she rejected him, as her family was moving to Vermont. She returns during the first season and while the two remain just friends for awhile, they eventually begin dating.
After breaking up, Vanessa discovers that Dan kissed Blair and tells Serena. She later discovers that Dan is writing a book about the UES and brings it to a publisher, who agrees to publish it. Afterwards, she moves to Spain and passes the royalty check on to Dan.
After being friends for years, Dan realizes he has feelings for Vanessa and the two enter into a relationship. Vanessa, an aspiring filmmaker, takes footage of Dan's sister Jenny Humphrey in her underwear rolling around with Nate Archibald in Central Park. Not knowing it is Jenny, she shows the video to Dan and the two have a fight. Wanting to make things right, Vanessa sends a poem Dan wrote to The New Yorker, titled Sluts. As a result, Dan gains some clout and an agent named Rusty Klein. Rusty also manages a novelist named Mystery Craze, whom Dan is attracted to. At a poetry reading, the two hook up, and Vanessa witnesses. She subsequently ends their relationship and begins dating Blair Waldorf's stepbrother, Aaron Rose.
He and Vanessa reunite after he sends her a toy from Japan to film. After briefly serving as frontman for the band The Raves, he hooks up with one of the instrumentalist's wives and later experiments with being gay. He eventually attends Evergreen State College but realizes he truly loves Vanessa.
In The Handmaiden's Tale, Vanessa appears at the Humphrey loft in Brooklyn to announce that her parents have let her move back to New York to live with her sister, Ruby. However, things are awkward between Vanessa and Dan, as they left things roughly before she moved, due to Dan telling Vanessa that he loved her as more than a friend. Meanwhile, Dan has begun dating Serena van der Woodsen, a fact that Vanessa is hurt by when she finds out. Despite this, they rekindle their friendship and hang out again. At Christmas, Vanessa reveals to Dan that her present is that she had a story of his, titled 10.08.05, sent to The New Yorker and will be published that summer. After unsuccessfully searching for the perfect present, Serena asks Vanessa for help in finding one. Together they create a video projector display of snow, since Dan wants snow for Christmas. However, Blair feels that Vanessa is harboring feelings for Dan and warns her to back off his and Serena's relationship. In the finale, Much 'I Do' About Nothing, Dan and Vanessa plan to hang out all summer.
In Chuck In Real Life, Blair and Chuck Bass team up to humiliate Dan and Vanessa by having Chuck seduce Vanessa. Their plan works when Vanessa is humiliated but she later tells Dan what happened. As revenge, Dan warns Blair not to confess her true feelings to Chuck; damaging her relationship with him (Pret-a-Poor-J).
In Seder Anything, Dan and Vanessa play a game of Never Have I Ever. She reveals that she slept with Chuck twice and that Rufus Humphrey confided in her that Dan was denied financial aid at Yale. In the finale, The Goodbye Gossip Girl, Dan and Vanessa are excited to be attending NYU together in the fall.Reversals of Fortune, Vanessa is turned off by Dan being integrated into the UES world when Rufus begins a relationship with Lily van der Woodsen. She's especially hurt when Dan ignores her to help Blair carry out a scheme to help Serena. However, the two makes amends and become friends again (The Freshmen). Meanwhile, the two become friends with celebrity student Olivia Burke. Dan begins dating her and all is fine until the three engage in a threesome (They Shoot Humphreys, Don't They?). Afterwards, Olivia is hurt, due to her seeing Dan and Vanessa ice her out during their threesome. She tells the two that they seem to have feelings for each other and leaves school to shoot a movie. Dan realizes that she may be right about his having feelings for Vanessa but Vanessa has begun dating Paul Hoffman, a student at Tisch (The Last Days of Disco Stick). On Thanksgiving, Vanessa's mother, Gabriela Abrams, comes to see her. While she visits, she observes Dan and Vanessa and tells him that he needs to be careful before admitting his feelings for her, since it didn't work out last time. Realizing he isn't ready to tell her, he encourages her to keep seeing Paul. In The Debarted, Dan confesses his feelings to Vanessa, who says nothing back. In The Lady Vanished, both bring dates to a dorm beach party throw by Vanessa's hall at NYU but hook up, realizing they have real feelings for the other. As a result, they begin a friends with benefits relationship but finally begin dating in The Sixteen Year Old Virgin.Soon after, Dan reveals he is applying to the playwriting program at Tisch. Not knowing that they are only accepting one NYU transfer, Vanessa applies as well and is accepted. However, Dan tells Willa Weinstein that she applied with a play she wrote based on one of his stories and Willa tells her father, who is on the admissions board. Even though Dan is eventually able to fix his mistake, Vanessa is hurt that he wasn't honest with her about how he felt about her getting in instead of him (Dr. Estrangeloved). In It's a Dad, Dad, Dad, Dad World, Dan discovers that Vanessa applied for an internship for CNN that requires her to move to Haiti for three months. When he tells her that he knows, she insists on staying in New York to save their relationship but he pushes her to accept the offer. She does so and the two plan to have a long distance relationship while she is gone. In the finale, Last Tango, Then Paris, Jenny catches Dan and Serena sleeping in the same bed. She sends a tip to Gossip Girl, and Nate, who is dating Serena, forwards the blast to Vanessa. As a result, she and Dan break up.
When Vanessa returns from Haiti, she finds that Dan has shut everyone out of his life. She is surprised to discover that Dan is the father to Georgina Sparks' newborn baby, Milo Humphrey, but tries to support him anyway (Belles de Jour). Meanwhile, Nate and his new friend, Juliet Sharp, try to get Dan out of the picture for Serena's affection by reuniting him with Vanessa. Their plan works and the two get back together (Double Identity). When Georgina leaves Milo behind, Vanessa offers to move in with Dan to help him raise Milo. Right before she does so, Georgina returns and says she is leaving with Milo. Despite this, Vanessa moves in with Dan anyway (The Undergraduates). Meanwhile, Dan has begun getting closer with Serena, a fact that makes Vanessa increasingly uncomfortable. In Goodbye, Columbia, Juliet frames her for sending in a false tip that Serena has an STD. She tries to tell Dan that she didn't do it, but leaves to go stay with her parents for awhile anyway.
In The Witches of Bushwick, Vanessa teams up with Juliet and Jenny to ruin Serena's life by separating her from Dan, Nate, Blair, and her family as well as getting her kicked out of Columbia. Their plan works, but gets out of control when Juliet drugs Serena into an overdose. On Thanksgiving, Vanessa returns to town and finds out what happened. After Juliet convinces her that she will lose Dan and all the Humphreys if they find out she was responsible, Vanessa singles out Jenny as the culprit. However, Jenny tells everything to Blair and informs Vanessa that she won't be able to lie her way out of that one. Vanessa then leaves again to go to her parents (Gaslit). She returns in While You Weren't Sleeping to apologize to Dan but he doesn't forgive her.
In The Kids Stay in the Picture, Vanessa overhears that Dan and Blair kissed and tells Serena, who doesn't believe her at first, but eventually learns she was telling the truth. In The Princesses and the Frog, Serena's cousin Charlie Rhodes sets Vanessa up to make it look like she wanted to ruin her blooming relationship with Dan. Dan falls for the stunt and thinks Vanessa is really out to hurt him. In the finale, The Wrong Goodbye, Serena is set up similarly by Charlie and she teams up with Vanessa to prove it. However, both are surprised when Rufus informs them that Charlie has stopped taking her medication and is at risk for a breakdown. The two search for her, along with Dan. Vanessa goes to the loft in case she shows up there and finds a story that Dan has begun working on. She is shocked by how good at is and encourages him to publish it. He refuses, saying it's a satire of his life and friends and doesn't want it to get out ever. After the two argue, Vanessa steals it and gives it to Simon & Schuster to publish. She asks them to forward her the royalty check, which she will pass on to Dan. She also says that she's moving permanently to Barcelona, since she has nothing in New York anymore.
Dan (on the UES): You hate this world.
Vanessa: So do you. Or so I thought.
-The Handmaiden's Tale (1x6)
Vanessa: You're at a polo match, in a $3,000 suit and your name's in the program. And after I take a bus across the state line to apologize, you ditch me for Blair Waldorf and totally disappear!
Dan: CeCe set me up with this suit, alright, and Jenny got a dress too, if you'd also like to make her feel bad about it. As for Blair, it's not like we're shoe shopping or sipping martinis, there was something going on with Serena.
Vanessa: And what is that?
Dan: I wish I knew. All I do know is that Lily's mother is very sick, my dad is struggling to keep it together, not to mention my family is just generally in the middle of a massive transition so please, please, give me a break with the "rich people suck" thing.
Vanessa: I don't care if you're rich, which you aren't by the way. Ride in a limo, break a hundred, that's fine. But if you're gonna be in this world, be yourself in this world because I actually like that guy. And I hope he's the one who turns up at NYU.
-Reversals of Fortune (3x1)
Dan: Vanessa. I love you.
Vanessa: I love you too.
Dan: Not really the reaction I was hoping for.
-The Debarted (3x12)
Vanessa: Actually, my dorm is throwing this huge South Beach Party today.
Dan: Great, I love parties.
Vanessa: And I'm going with Paul.
Dan: I love Paul.
-The Lady Vanished (3x14)
Vanessa: I've always only wanted you, Dan. But even I have my limits.
-Touch of Eva (4x4)
Dan: I'm not gonna chase after you, Vanessa.
Vanessa: And I wouldn't stop for you if you did.
-While You Weren't Sleeping (4x16)
Vanessa: When are you going to realize you were a better person before the day you asked Serena out four years ago?
Dan: When are you going to realize I had a better life before you climbed up my fire escape four years ago?
-The Wrong Goodbye (4x22)