A 20th century Human woman in the book by Todd Matthews, Vanessa was an attractive blonde, a married woman who had an inheritance. At the casino, she had taken up with Texas, who was conspiring with her to murder her husband while squandering her money. He tended to push her into unwise gambling situations, fostering her dependence on his advice, and eventually causing her to rely on his monetary winnings as well.
A physical representation of Vanessa, along with the setting and other characters of the novel, was created by an unknown alien presence for a Human astronaut named Colonel Stephen Richey on Theta VIII in 2044 when his ship, the Charybdis, crashed there. The Theta VIII alien interpreted the character described in the book and replicated her in a black evening dress. An away team from the Federation starship USS Enterprise-D entered the hotel in 2365 and found the situations from the novel still being re-enacted in the building.
When Data approached the blackjack table, Texas included him in their repartee. Vanessa intently followed Data's simplified description of the game, and whistled in amazement at the android's dexterous card shuffling. While Texas advised Vanessa to take another card, she lost with that deal, with Texas able to reach blackjack. However, Data was also able to achieve blackjack with a play of statistics, despite Texas advising against his taking additional cards. Vanessa again followed closely to Data's simplistic explanation of the logic of taking another card and nodded in agreement.
After an investigation of the Royale surroundings that included the discovery of Richey's corpse, Data returned to the casino's blackjack table where Texas had been watching his chips. As he approached, Vanessa was expressing worry about her monetary situation, examining her purse despite Texas's advice that it was bad luck to count chips at a table. While Data queried Texas about the reason for the anomalous hotel, Vanessa took another card and lost, expressing that she was "losing her shirt". Data seemed surprised by the slang comment, visually noting that her somewhat revealing clothing had not included a shirt. Texas took this opportunity to point out to Data that he was there to make sure that Vanessa turned her luck around, while attempting a somewhat flirtatious embrace. Oblivious, Vanessa asked Texas and Data about her next hand. While Texas advised her to take another card, Data pointed out that the odds favored standing pat. She took Texas's advice and lost, exclaiming her total above 21 was "too many" as she realized she was out of money. Texas again attempted to embrace her again, this time to her notice, assuring her that he would take care of her. Data awkwardly observed the interaction.
As the storyline continued to play out around the away team, with Mickey D murdering the bellhop, Vanessa and Texas moved on to the craps table. The away team returned to the casino to observe Vanessa rolling a two, or "snake eyes", which Data noted was not desirable. At this point, Texas and Vanessa were both losing, with Vanessa expressing concern that she might not even be able to afford lodgings. Texas again assured her that he would take care of her, following with another bout of intimate contact, which surprised the vulnerable Vanessa, this time observed by both Data and Worf.
As Data explained the rules of craps to William Riker, he noted that the random fortune involved was why they called it "gambling", Vanessa was again visibly impressed with Data's summation of the situation. With another bad dice roll from Data, Vanessa commented to Texas "so much for your new turkey", a reference to Texas's desire to have himself and Vanessa benefit from following his plays.
After Data corrected the dice weights for fair rolling, the away team began their planned winning streak to secure their escape from the casino. With Texas's plan to follow on to the winning gamblers working, Vanessa complimented his brilliance. Riker, playing the role of the investor from the novel, gifted Vanessa and others with complimentary chips to celebrate their victories. After Riker's gift, Texas declined to stay included in the bets. When the away team broke the bank, Vanessa and the others happily congratulated them as they departed. (TNG: "The Royale")