|Portrayed by||Karen David|
|First Appearance||Series 6, Episode 1|
|Last Appearance||Series 6, Episode 20|
|Occupation||Head of Spanish,Spanish Teacher|
|Sibling(s)||Three unnamed/unseen sisters|
|Romances||Tom Clarkson (Deceased)|
Cesca has always found teaching Spanish easy - her mother is a native Spanish speaker, having taught Cesca and her three sisters the language from year dot so she’s a natural. Cesca teaches for the long holidays and a chance to travel the world. Highly attractive, she’s sexually confident, and is flirty even with the students. Her classes are bold and fun. Cesca loves clubbing but is bright and vivacious enough to run her classes the next day. She’s young enough to burn the candle at both ends, and does her job well. She’s compassionate and often finds herself drawn into other people’s problems, a personality trait which often finds her in hot water.
Cesca Montoya arrives at Waterloo Road and is instantly liked by other staff members by her excellent Spanish speaking skills and by her students, most likely from her appearance.
Year 11 pupil Harry Fisher, son of headmistress Karen Fisher, suspects that his dad, Charlie Fisher is having an affair with Cesca after finding a suspicious message on his dad's phone. Harry and fellow Year 11 pupil Sambuca Kelly go to the location mentioned in the message where they find Cesca and Charlie walking together, Harry takes a picture of this on his phone. Karen confronts Cesca about the situation after being shown the picture by Harry. Cesca insists that she is not having an affair with Charlie, but instead, Charlie is having an affair with someone else who is close friends with Cesca. Cesca directs Karen to the woman's apartment.
Cesca reluctantly runs a drug self-awareness programme for her Year 11 pupils. Her intentions backfire when Sambuca Kelly asks for money to purchase drugs from her close friends Amy Porter and Lauren Andrews so she can just throw them away afterwards in order to protect them from it. Amy misinterprets this when she sees Sambuca giving Cesca the drugs after purchasing them, Amy then assumes that Sambuca was ratting herself and Lauren out. When Karen finds out, Cesca struggles to unravel the truth, but just manages to explain it to Karen to satisfactory and just manages to save her job, although Karen still suspends Sambuca when it Amy's scheme to frame Sambuca for the drugs succeeds, despite Cesca being able to explain Sambuca's good intentions to Lauren, who also helped Amy frame Sambuca.
When new pupil Kyle Stack unleashes a dangerous dog on Year 13 pupil Bex Fisher during a Spanish lesson, the dog goes beserk and starts attacking Cesca as well, but Cesca is then saved by Year 12 pupil Jonah Kirby, once the dog is locked in the classroom alone, Cesca is seen crying into Jonah's arms; the dog is then taken away by the police and put down. Cesca later thanks Jonah for saving her, this episode shows the first hints of Cesca's sexual attraction towards Jonah.
Cesca begins a extra Spanish lessons during lunchtime, which only Jonah bothers to attend, Jonah struggles with his accent as he intends to get an A in his Spanish A-level. Cesca explains that if he "wants to speak fluent Spanish" he just has to "work on it", as she walks away, Jonah shows signs of attraction to her. Cesca later shelves the extra Spanish lessons during lunchtime because just having one pupil showing up is not enough to sustain the programme. At the end of the day she tells Jonah she'll see him tomorrow as lessons will run again. They are later seen texting.
Near the beginning of the day, Jonah attempts to kiss Cesca, but Cesca slaps him away. Jonah insists to Cesca that there is "something going on" between them as Cesca continues to find it increasingly difficult to resist his seductive charm. After head of English Tom Clarkson is brutally beaten by Matthew Gurney, the father of his son's boyfriend, Cesca helps Tom home and calls Jonah at her house to comfort her, the two then share their first kiss before Cesca sends Jonah away, knowing that what she is doing is wrong.
Cesca tries to distance herself from Jonah by trying to date Tom, who is now suffering from agoraphobia due to the beating, this causes Cesca's attempt to date him to fail. After school, Jonah shows up at Cesca's front door, insisting that he can't stop thinking about her, Cesca then gives in and sleeps with Jonah, this is later revealed to be Jonah's first time.
Karen's son Harry's desperation for attention goes out of control when he steals her phone and starts sending offensive messages to Karen's colleagues, the message Cesca receives causes her to suspect that Karen is aware of her affair with Jonah. Cesca is relieved when she finds out that the message was not from Karen and that everyone is still oblivious to her relationship with Jonah.
Jonah gets fed up of being Cesca's "dirty little secret" and gives her an ultimatum that unless she accepts that they are now in a serious relationship or their over. Tom has now recovered from his agoraphobia and attempts to return Cesca's apparent affections, but Cesca turns him down when she tells him that she has started seeing someone else; Cesca accepts that herself and Jonah are now in a serious relationship and start seeing each other properly.
Cesca discovers that she is pregnant with Jonah's child and Jonah has now decided that he wants to leave school and get a full time job so that it is legal for Cesca to be seeing him. When Jonah finds out the truth, he goes to a big party after school organised by Finn Sharkey and Jonah's best friend Ronan Burley, where Ronan and Vicki Macdonald are still curious as to who the "mystery girl" is who Jonah is dating. Jonah went to the party to celebrate his "new life" referring to him leaving his education to live with Cesca and the baby. Cesca arrives at the party when things get out of hand and she sees Jonah behaving drunkly and irresponsibly, which leads her to question his maturity.
Cesca decides to have an abortion, but ultimately decides that she couldn't go through with it, while Jonah's sister Ruth Kirby becomes progressively more suspicious of her brother's behaviour. After school has ended, Cesca reveals to Jonah that she chose not to have the abortion, Jonah then proposes to Cesca, which she accepts; Ronan then walks in on them, making him the first person to find out about their relationship, Jonah makes Ronan swear not to tell anyone, which he accepts.
Ronan struggles to keep the secret in, and tells his girlfriend Vicki; Vicki then tells Cesca to try not to take advantage of Jonah, leading Cesca to mistrust Ronan. Deputy head Christopher Mead becomes suspicious of Jonah and Cesca when Cesca falls off a ladder and Jonah appears unexpectedly worried and refers to Cesca by her first name rather than her second name. When Cesca is rushed to the hospital due to her injury, Jonah arrives and they kiss just as Chris walks in on them. Karen consults Cesca about the relationship, where Cesca reveals that they're engaged and that she's pregnant. Karen calls in Marcus, who becomes furious due to his son's actions. Jonah and Cesca are then seperated by Marcus and Cesca is sacked and put under house arrest.
Due to the seriousness of the dilemma, the story was on the front page of several local newspapers and several new rules were created for the school, with basically all of them preventing pupils from having one-on-one or private lessons with teachers or anything else that could lead to a similar problem to what happened with Jonah and Cesca. Cesca and Jonah decide to prove that Cesca was not just manipulating and taking advantage of Jonah by proving that they are genuinely in love by running away to get married. Cesca and Jonah escape to services where they are encountered by Chris Mead who later alerts the school and the police of the situation. But the police do not arrive in time to prevent the couple from getting married. They arrive shortly after they are wed and Cesca is arrested by the police while Jonah is sent back to school where he is reunited with his father and sister. This is the final appearance of Cesca, Jonah and his family, Marcus and Ruth, due to Cesca being arrested and Marcus having his children leave the school grounds.