Much of Jessa's childhood is unknown. Her parent's split-up when she was little, and she has mentioned to having a strained relationship with her mother. Her father has since remarried. She has also mentioned having had an uncle who died of AIDS. Shoshanna is her younger American cousin, who's believed to be from her mother's side of the family. She met Hannah and Marnie while briefly attending Oberlin College, and left after developing a heroin habit. She has since spent the last several years traveling the world. At some point, Jessa contracted HPV, but told Hannah that "All Adventurous Women Do". When Jessa thinks that she is pregnant, she decides to go to New York in order to figure out what she should do.
From the HBO Official Site:
"Jessa is beautiful, British, an occasional nanny who has travelled to as many different countries as she's had boyfriends. Back in New York for the first time in years, she moves in with her cousin Shoshanna, ready to shake up her friends' lives a little bit."
Jessa arrives to Shoshanna's apartment in the Pilot. She then later goes to a welcome party thrown by Hannah and Marnie. While Hannah is happy to see her, Marnie has not liked Jessa since she slept with one of her friend's boyfriends back in college. The situation is made worse when Jessa asks if Charlie (Marnie's boyfriend) is single, and letting Hannah drink Opium tea. When Marnie confronts Jessa about her irresponsible behavior, she reveals the real reason to why she came to New York.
Continuing on from the pilot, Jessa has decided to end her pregnancy. She has Marnie make an appointment for her at an abortion clinic in Vagina Panic. While on her way to the clinic, she ends up stopping at a bar, where she meets a random guy. They proceed to go into the bathroom to have sex, where Jessa discovers that she has started her period.
Jessa get's her first job as a nanny in All Adventurous Women Do. She meets and has a connection with the father Jeff. Who later forgives her for briefly losing his kids in Hannah's Diary. She meets an ex-boyfriend in Hard Being Easy. They have sex in Shoshanna's apartment while Shoshanna was still there. Afterwards, Jessa tells Shoshanna that she's not ashamed over what happened.
In Welcome to Bushwick a.k.a. The Crackcident, Jessa receives a mysterious text while at a rave with Hannah, Marnie, and Shoshanna. The text turns out to be from Jeff. She ends up abandoning Shoshanna, who accidentally smoked crack, to hang out with him. After throwing a bottle of wine at a group of male partygoers, Jeff get's jumped and has to be taken to the hospital. He later admits his attraction to Jessa, but when she rejects him, he fires her.
Following her altercation with Jeff, Jessa goes to Hannah and Marnie's apartment in Weirdos Need Girlfriends Too. She ends up forming a bond with Marnie, who's depressed over ending her relationship with Charlie, and the two end up going out. While at a bar, they get picked by a wealthy older guy named Thomas-John. They end up at John's place, where Marnie and Jessa start making out with each other. When they spill a glass of wine on his carpet, John throws them out.
Jeff's wife, Katherine, visits Jessa in Leave Me Alone. She initailly wants Jessa to come work for her again now that she and Jeff are separated, but reliazes that it's not a good idea. She does however tell Jessa that the reason behind her behavior may be the fear of actually being an adult.
Jessa sends an email-blast out to Hannah, Marnie, and several other of her closest friends in She Did about a secret party she's throwing. When everyone shows up for the event, it's revealed to be a surprise wedding between Jessa and Thomas. During their vows, Jessa explains that she didn't like him at first, but that his stories of finance and travel made her fall in love with him.
In the season premiere, Jessa and Thomas-John return from their honeymoon.
In I Get Ideas, Hannah sees Jessa and Thomas-John's relationship, which causes her to question her own with Sandy. Jessa is now living with Thomas-John, and he buys her anything she wants.
In It's a Shame About Ray, Jessa is to meet Thomas-John's parents. Though they are both nervous, they go to the dinner. Thomas-John's mother dislikes Jessa for her lack of work ethic and thinks she is using her son. This causes Jessa and Thomas-John to have a fight later that night, in which she leaves his in exchange for money. She goes to Hannah's house and is genuinely, visibly upset.
In the following episode, it is shown that Jessa is staying with Hannah. She tells Hannah that her first book isn't going to matter to her or readers. Hannah calls her depressed, which she denies.
In Video Games, Jessa and Hannah go to meet Jessa's father. He is extremely late in picking them up. Her and her father appear to get along fine, until the following morning. Her father and her have a brief argument, in which he promises to do better. However, the next day, he drops the two girls off at the store, and forgets to pick them up. The following morning, while Hannah is sleeping, Jessa leaves. She doesn't return until the third season, being absent for the following three episodes. Though, in the season finale, Hannah attempts to call her, and leaves a reprimanding voice mail.
At the start of the season, Jessa is staying at a rehab facility as per her grandmother's request. However, she is uncooperative and obnoxious during group therapy and antagonizes other patients. The exception is a British patient named Jasper, with whom she talks quite often. The last straw for the facility becomes when Jessa is caught having sex with another female patient, resulting n her being kicked out. She calls Hannah, their first contact in months, and asks her to give her a ride. Hannah ventures out with Adam and Shoshanna to retrieve her. Hannah tells her her behavior has not been okay, and she has to start being a better friend, to which Jessa agrees.
In Dead Inside, Jessa talks with Shoshanna about the concept of death. She reveals she had a friend who died, and Shoshanna encourages her to visit the grave. However, Jessa learns her friend isn't dead at all, and lied to her to get away from the bad influence Jessa was.
In Only Child, Jessa begins working at a children's clothing store. She likes it at first, but becomes increasingly bored.
In Beach House, Jessa joins the girls on a weekend getaway at a beach house supplied via Marnie's mother's friend. The trip ends with the girls all arguing with each other, and then returning home.
In Incidentals, Jasper tracks Jessa down, and she relapses. The two spend their time together getting high.
In Role-Play, Shoshanna arranges a dinner to reunite Jasper and his daughter in order to drawn him and Jessa away from drugs and each other. Shoshanna is successful, despite Jessa's dismay.
In the penultimate episode, Jessa is hired by Beedie, an artist being featured in Soojin's gallery.
In the season finale, it is shown that Jessa and Beedie have grown closer, and Jessa agrees to take part in helping Beedie commit suicide. However, after taking many pills, Beedie decides she doesn't want to die, and Jessa calls for an ambulance.
Season 4 Edit
At the start of season 4, Jessa is still working for Beedie, who was stomach-pumped and survived. However, Beedie's daughter arrives to take her to live with her in Connecticut. Though Jessa protests, Beedie is forced to let her go and the two part very amicably.
In Female Author, it is shown that a friendship has begun between Jessa and Adam. They go to AA meetings together, and hang out outside as well. While walking together through the streets, Jessa stops to pee. However, the cops see and attempt to give her a ticket. After she makes rude remarks and rips the ticket, she is put under arrest. Adam, who tries to defend her, is also arrested. After release, Jessa tries to play the situation off, but Adam is very upset. He calls her reckless and doesn't want to be her friend. Very heartfeltly, she responds that she needs him to be her friend.
In Cubbies, Jessa gives Marnie disagreeable feedback on her music.