She showed up at Lex's charity gala and got herself invited to the mansion. She proposed Lex help her father take over LuthorCorp, and he made a counter proposal that they take over both their fathers' companies together. Lex was led to believe that Harry needed Lex's shares to take LuthorCorp away from Lionel. He played on Lex's hatred of his father to persuade him to go in on the deal.
Victoria agreed with Lex's plan to take Harry's company as well as Lionel's, but she went behind his back to steal information off his computer. Clark caught her going through the files on Lex's computer. She was attacked in the bathtub and nearly drowned by an invisible assailant. Victoria accompanied Lex to a reception held by Bob Rickman as they continued to work together to bring their fathers down. Eventually, Victoria revealed herself as having tried to betray Lex by stealing information from his computer, but Lex countered that that information was fiction, and she and her father bought the worthless Cadmus Labs, allowing him to buy her father's company.
Lex never saw her again, except via a photograph given to him by Roger Nixon, in which she and Lionel are depicted as having sex.
While under the influence of Red Kryptonite, Clark used his X-Ray vision to look through Lex's files at the mansion. One of them was a file named 'Victoria' which Clark presumed to be about Lex's ex. (Temptation)