Eva makes her first appearance in Belles de Jour, in a short flashback when it's shown she saved Chuck Bass after he was shot (in Last Tango, Then Paris). It's revealed it was a nightmare Chuck had about the event, and the two are shown to be in a relationship. They arrive in Paris together.
They move into an apartment together, and Eva gets Chuck a job working for her uncle in a bar. After Chuck sees Blair Waldorf in the city, he tells Eva that his grandfather left him a small inheritance that he wants to use to move them to India. Eva agrees to go with him, and Chuck prepares to become Henry Prince forever and abandon being Chuck Bass. Before they can leave, Blair finds and stops Chuck from leaving his old life behind. After thinking it over, he apologizes to Eva for lying about who he was and asks her to come back to New York with him (Double Identity). When they get back to New York, Eva is in awe of the city and Chuck's place in it. He plans to bring her to Fashion's Night Out to meet his family, and Lily van der Woodsen is excited to meet her. While shopping for a dress, Eva runs into Blair. She tries to introduce herself, but Blair takes the opportunity to belittle Eva and ruin her self esteem. As a result, Eva decides not to attend the event but changes her mind when Chuck convinces her. At the event, Rufus Humphrey and Eric van der Woodsen are still angry at Chuck for sleeping with Jenny Humphrey and decide to tell Eva what a bad person he is. To protect her, Chuck shoos her aside and pretends not to know her. Saddened, she tries to leave but is stopped by Chuck; who decides to tell her everything about himself, the bad stuff included. After hearing it, she decides to stay with him because she has seen the wonderful man he can be (The Undergraduates).
In Touch of Eva, Chuck gifts Eva a very expensive Cartier watch and announces his plans for a five million dollar charity. Later that day, Blair sees Eva exchange the watch for cash and films it. She goes to The Empire to see Chuck, and shows him the video. Along with Ivan, Chuck's valet, Eva explains that she sold the watch to give the money to Ivan's family, who is close to losing their house. Chuck decides to let Eva choose which charity he will give his money to, and she and Blair go to see the different organizations. Still wanting to take her down, Blair extorts information about Eva and sends it to Serena van der Woodsen and Dan Humphrey to find something bad about her. While investigating, they find that Eva was a prostitute in Prague. Blair decides to out her at Chuck's charity gale, and Dan tells Nate Archibald, who tells Chuck. He pretends to already know, but it becomes clear he had no idea. He confronts Eva about it, but they decide to move past it. At the gala, Blair tries to tell Chuck but he replies that he doesn't care. When Blair sees Chuck name his foundation after Eva, she grabs the envelope containing his passport from Ivan and plants it in Eva's suitcase. She tells him that she found it in her suitcase, and upon going through it himself, Chuck sees it inside. He realizes Eva knew who he was all along and breaks up with her, then telling her to go back to Europe. She begins to pack, and soon after he learns from Lily that the envelope with his personal belongings just arrived that day from Paris. Chuck realizes Eva really didn't know he was and runs to stop her. However, she still plans on leaving and does so after telling him not to forget the good man he is or her. This is Eva's last appearance in the series.