|This article is about the Netflix Series character. You may be looking for the book character.|
|“||What I meant, what I mean is that, if I hadn't moved away, if I hadn't let her start dating Justin, if I'd been around to help her through it, she'd still be alive today.||”|
|— after being asked about her text about Hannah having bad taste in guys, in "Tape 7, Side A"|
She is first introduced in the flashback, taking place at her going away party. She and Hannah bet against Clay, and Kat owes Hannah five dollars. She welcomes Clay and hands him a beer. When she sees Bryce flirting with Hannah, she tells Hannah to stay away from him. After Hannah goes away to get a beer, she tells Clay to make a move. At the time, she is dating Justin, although Hannah clearly likes him. After she moved away, Kat video chatted Hannah and tells her that he is all hers.
Kat is back when the Baker's handed out subpoenas for their lawsuit, since Kat is on the list that Olivia found in the back of Hannah's closet. When she arrives at the taped deposition, Kat makes it clear the boys, specifically jocks at Liberty High are disrespectful and believe they can do whatever they want to girls. Dennis states that Kat texted Hannah more than once that she had a bad taste in guys and Kat then claims that if she hadn't moved away, she wouldn't have let Hannah date Justin and she would have been around to help her through the pain he and others caused her and that Hannah would still be alive today. When Dennis asked if she was talking about Justin Foley, she states that Justin is dead to her.
Although she has only appeared on two occasions in the series, Kat is shown to be a kind and caring person and is the only true friend that Hannah ever had and was shown to care for her deeply. Like Hannah she is shown to have a witty sense of humor and is very kind towards Clay and encouraged him to go after Hannah.
Kat is shown to be well aware of the cruelty of many of the boys at Liberty High as she later reveals during her deposition and warned Hannah to stay away from Bryce, however she was unaware of what Justin was capable of as it was her who encouraged Hannah to go after him and this was unfortunately the beginning of the chain of events that would ultimately end in her friend's tragic suicide.
During her deposition Kat strongly expresses her disdain for the treatment suffered by girls at her former school and is shown to be utterly devastated by her friend's death and claims that had she not moved away and encouraged Hannah to start dating Justin, she would still be alive, showing that Kat blames herself for Hannah's death to a degree and regrets not being there for her when she needed help. She appears to be aware that Justin was the beginning of the end for Hannah and makes it clear that she now hates him and that he is dead to her.