Janie is the young day care worker who works at the day care where Lucy and Jasper go after school. Unbeknownst to them, she is dating their father Deran.
After Lucy and Jasper's mother died from brain cancer a year before, Deran took his children to a day care center (where Janie worked) after school while he was at work. Over time, both Janie and Deran became attracted to each other, and then started dating. However, because Janie was much younger than him, her libido outmatched his naturally low one. Deran decided on using male enhancement cream to boost his libido to match her sex drive.
Janie is first seen when Deran comes to pick up his kids, but finds Jasper with a severe nosebleed. When it doesn't stop, she goes to call 911. When she gets back Jasper's nosebleed has stopped, but Lucy has collapsed.
When Jasper gets sick too and the cause of both children's illness is testosterone, Gregory House has eliminated everything but an environmental cause and wonders aloud if anyone else at the day care got sick. Deran assures him no one is, but when House asks how he knows, he assures House he would have heard.
House figures out that Deran is in a relationship with someone at the day care. After going to the day care and asking a girl if she is suffering the same symptoms, Janie comes along and House realizes she and Deran are seeing each other - that's how Deran would know if any other kids were sick. After accusing her of exposing the kids to something, and her denying she's ever been to their house, he notices her upper lip has recently been waxed, but she's had no other spa treatments. He realizes she must have had thick hair to leave at lunch to have it removed and realizes that she's been exposed to testosterone as well and that Deran must be the source. It turns out Deran had been using testosterone creme to boost his libido.
At the end, Deran reveals to his children he's dating Janie and they all leave the hospital together.