Throughout the film, Marina engages in an extreme form of cyberbullying against Laura. From the examples in the book, Marina both impersonates Laura online to ruin her reputation by taking over her Facebook account, and she also creates significant fear in Laura by harming those she is close with. For Marina, this is retaliation to what she felt as bullying from Laura, when Laura lied to her about her birthday party to keep her from attending.
During Marina's takeover of the account, she posted graphic videos of the deaths of Laura's friends. This content caused Laura's peers to start cyberbullying her as well. Laura started receiving mean comments and messages, some telling her she should die. Laura's online friend count continually drops throughout the film, and Laura is eventually suspended from school due to the contents of her account. There is a clear link to the characters' emotional well-being and the effects of cyberbullying.
Friend Request acts as a commentary on the issue of internet addiction. At the start of the film, Laura's professor is lecturing about internet addiction. Laura is on her phone during this lecture, and the professor calls her out as an example of internet addiction disorder. Before her account is hacked by Marina, she's posting and messaging others extremely frequently. After the hacking, Laura is frequently seen checking her Facebook page and reading all of the awful comments, even after her friends try to convince her to stop, as it is harming her mental health. Laura's self-worth is based around her reputation online, so when her friend count has reached zero by the end of the film, Laura also becomes a lonely outcast in real life. This is how Marina started out in the beginning of the movie, an outcast with no friends on social media.