Ali first came into contact with House when she came with her father, who was suffering from the common cold, to the clinic. In order to keep the father quiet while he examined him, House role-played as the father, telling Ali what she wasn't allowed to do in a mock-authoritative voice. Ali thought House was funny and was relieved that her father wasn't really all that sick.
However, after the clinic visit, she started leaving House a lot of messages. Cuddy became concerned that the girl was trying very hard to get in contact with House, but House wasn't at all concerned until Ali showed up again at the hospital. When Ali asked why he didn't call her back, he said he was "waiting a few years". Ali was flattered and, although she said she was only there to thank him for taking very good care of her dad, as she left, she told him he would only have to wait six months. When House returned to his office later, he found a new calendar with Ali's birthday marked in bright red.
Ali returns in the next episode, Lines in the Sand, as a patient in the clinic. She's complaining about a cold, but as House reaches for his stethoscope, Ali removes her top, exposing her breasts, just as Foreman bursts in looking for House. Cuddy starts getting really concerned about Ali, nearly getting a restraining order against her. House thinks it is all much ado about nothing, but takes the opportunity to make Cuddy even more miserable, by saying "You can't stop our love!" as she enters a crowded meeting room.
In truth, it is clear that although House is flattered, he's not really interested in pursuing a relationship with Ali. However, he has no intention of hurting her.
However, Ali shows up straddling House's motorcycle. After having a discussion about age of consent laws, Cuddy shows up and threatens to have her arrested if she shows up again.
Cuddy makes good on her threat as Ali shows up again. Cuddy takes her to her office and demands House make it clear to her that she should never show up again. House gives her a few lines from Casablanca, and then diagnoses her with a fungal disease that lessens inhibitions and judgment. House manages to convince her that she's not really in love with him and that it's only her lack of inhibitions speaking. Whether the diagnosis was real or not, Ali leaves and never comes back.