One of the first times we saw Vanessa on the live feeds, she was having an emotional meltdown. She missed her girlfriend but most of all, she said, she could not handle the way people in the house treated each other. The bullying was weighing on her, particularly how they all treated the shy, socially inept Steve. Those of us who knew Vanessa as a steely poker player where shocked by the flood of tears as well as her rapid-fire speech pattern. It humanized her and made her less of a target, despite her Duke degree and 2.5 years in law school. Being emotional worked for her, it made her seem less of a threat and more vulnerable.
But as the weeks and then months went on, the vulnerability turned into paranoia and whatever bonds she felt she had created with her allies disappeared. She was constantly hyper-vigilant for anyone who threatened her position in the game, she dissected everyone's incentives to determine their true intentions, she questioned and berated them to prove their loyalty rather than convey a sense of mutual trust. In a game that is built in large part on building interpersonal relationships, she failed to form real attachments or even to fake sincere connections. She made it too apparent that everyone was a chess piece that she was moving around the board and that she had no personal connection with anyone. She missed the basic concept of a final two deal - that each party must believe the other party intends to keep the deal. Without that, you have no option but to win every competition at the end.
Vanessa has created with Steve a solid alliance, the Students of Sound (SOS). They had a common bond, both super smart, well-educated people who were drawn away from academic pursuits to do what they love, pursue music. Steve relied on her and confided in her. But he did not trust her and that was Vanessa's fatal flaw. She didn't read Steve right and thought that he needed her and trusted her more than he did. She thought the socially awkward Mommy's boy would cling to her and feel beholden to her as his only true ally. She thought their Final Two SOS meant something to him and that she was his only friend in the game. She didn't realize he had a Final Two with Johnny Mac, also built on super smart, well-educated people with a strong love of music. And she didn't realize that Steve's had waited his entire life to play this game and he was not going to make any of the mistakes he had seen over sixteen years of watching every iteration of Big Brother in an English-speaking country.
Vanessa misread that Steve was a superfan first and would do and say anything to win the game. For all his retching and crying he never lost his superfan mind. He didn't want to be Cody and he wanted to Neda her so bad her could taste it which meant he had to win part 3, win the final HOH, and put his future in his own hands. He was naive but not stupid; he knew Vanessa would never take him to the end. Vanessa, for all her talk about needing to understand people's incentives, some how thought that Steve would act contrary to his best interest and take her to the end. But he was incentivized to be the one to vote Vanessa out of the game, and land the big kill everyone in the house had been gunning for.
Had Vanessa kept Austin, with whom she also had a Final Two deal from very early in the game, he would have thrown it to her thinking she'd take him over Liz. His incentive was to get the money and the girl and he thought the best way to do that was to let his two closest allies, Liz and Vanessa, battle it out in the end and then take him. But Steve could not risk that and so, to use language Vanessa would understand, she put her tournament life on the line in a race. That's not great poker strategy and it's not great Big Brother strategy.
*Steve said he never went by Steve in his life but the producers had him change it.