Vriska is John's patron troll that was clear. She helped him the only way she could, which might seem a bit mean of her at the moment, but looking back to it, John was glad that she did the things she did. As Vriska interacted more and more with John, small but very real flushed feelings began to sprout in her. Even after the Nic Cage video that John sent her, her feelings for him kept growing and growing.
When John was going god tier, Vriska was happy that it would be nearly impossible for him to die, but it also pained her to see him die at all. Now she understood why it was hard for Tavros to kill her when she was going god tier. She watched John die on his quest bed by Bec Noir.
After that, when they were talking, Vriska desperately wanted to tell John the feelings she has for him, but all she should say was that they could go out for a date once everything was over. When John said he would do it, Vriska was content right then. Sadly, that contentment didn't last.
When it was time for the final match between Terezi and Vriska, and Terezi did what she needed to do, Vriska couldn't help but think about John, and how sad he would be once she was gone. As her last thought, Vriska said her apologizes to John.
The dream bubbles let Vriska do things then would keep her mind busy, and not let it slide into a depression. She met many people there, including her chatty dancestor. Things were going well for her, so when John showed up in a dream bubble, her flushed feelings for him came running back to her, hitting her like an animal-like person pouncing onto you. Vriska didn't let it show though, knowing that it would only go against her plan.
Now that John has been seen in the dream bubbles, Vriska can't help but think of her feelings for him, and what they had planned to do when everything is over. She wonders how they would be able to go on a date, but she quickly forgets about it for her plan.
Those feelings still linger in her, even if John doesn't feel the same way back. Vriska won't let anyone know of the flushed feelings that stab at her when she is with John, because she doesn't want anyone to tease her or bother her about them.