According to Channel 4's official Hollyoaks page Nico is "intelligent, funny, but with quite a dark streak", as well as being quite mature for her age, as a result from going to care home to care home. It also mentions that although Nico has a tendency to push people away, this is down to a fear of rejection and in reality she just wants "to be loved and to be a part of a real family" and that she is "looking for a place in the world."
Nico kills Carly Bradley (Sophie Wise) when she sees her attacking Sienna. Sienna helps her cover up the crime. Later, Sienna and Nico find out that Carly was Sienna's boyfriend, Ben Bradley's (Ben Richards) daughter after he told them about Carly's death. The next day, Nico was arrested for Carly's murder after her phone was found at Ben's house where Carly died. Later, she was released by the police. Two weeks later Nico finally tells Maxine Minniver (Nikki Sanderson) the truth about Carly's death. Nico also tells Dylan on the day he is sentenced to six months for dealing in legal highs. Dylan promises to keep Carly's death a secret before his death.
Nico kills Patrick when she overhears him revealing that Ben will find out who killed Carly. Nico walks into Patrick's room where Maxine decides not to kill him. She tells him she can't let Ben know. And kills him.
When Nico stops taking her medication for her kidney, it begins to fail. Theresa McQueen (her previous donor) supports her. However Nico decides to spike some wine to kill Theresa so she can have her other kidney. But soon she becomes friends with Theresa and tries to get rid of the wine. This fails. Nico falls asleep on the sofa and Theresa drinks half of the wine leading her to collapse. Nico calls Sienna who immediately comes to her aid. Sienna promises that she won't tell anyone what Nico has done. Sienna pours the wine into the lake and makes a phone call to Trevor saying that Nico is out of control. Nico over hears the convocation and confronts her mum. This leads to a fight which smashes the wine bottle. Nico picks up the smashed bottle and stabs Sienna; before leaving her for dead.