Maddie Harper was a Science teacher at Elmsmere Manor. First appearing in Farewell, she was Lizzie Baker's replacement after Lizzie, Dexter, Nero, and the Baker-Harris twins left to go to America. She does not appear in Series 9.
Maddie first appears in Farewell as Lizzie's replacement. Mr Nunn takes a liking to her in her first appearance and agrees to give Maddie the tour but his liking for her fades when she reveals she will be teaching PE too, resulting in Mr Nunn wanting to prove he is the best PE teacher Elmsmere has.
In Tattoo, Mr Bell also takes a liking to her and when he finds out she was evicted from her flat he wants her to move in with him, thinking it could be an opportunity to bring the pair together. He leaves a letter in her pigeon-hole but it gets pushed away by a tablet Bell sourced from abroad. Bell asks Maddie if she got what he left, and Maddie, thinking Bell was talking about the tablet, says yes and Bell offers to help her setup, thinking she wants to move in, but Maddie thinks Bell wants to help her setup her tablet.
Maddie catches Bell packing his car with her stuff and Bell realises there had been a misunderstanding and tells her. Maddie is happy, thinking she has her own flat, but doesn't realise Bell will be living with her. She tries getting Bell to leave by reminding him indirectly so she wouldn't sound impolite but to no avail. Bell gets into bed with Maddie and she, due to her army training, punches him in the face, and there he is sent to hospital and likely explains everything to Maddie there.
In the following episode Maddie asks Bell if he could take her son Jack with him on a museum trip. Bell agrees, thinking it could bring him and Maddie further together, and potentially start a friendship between Jack and CJ. Maddie ends up being unavailable, having to look after her mum. Jack stops off at the service station to buy a twix bar and ends up calling his mum when the bus leaves. Bell realises someone is missing and asks CJ to help him find Jack.
They get a taxi and find the service station. Bell mistakes another boy as Jack and tells him to get in the car, but realises it isn't Jack, but the dad sees and calls the police. Bell refuses to pay the taxi driver and he also calls the police. CJ finds it all amusing and is recording it on his phone.
Bell is let go and when he gets back to school he is told by Maddie that Jack wonders off a lot and he just wondered off. He realises CJ received a call earlier from Maddie saying this but didn't pass it onto Bell. Jack later moved into the Carter flat and shared a room with CJ.
Maddie and Jack are still living with Bell and CJ but Maddie is desperate to get Bell and CJ to move out so she and Jack can have the flat to themselves. In Quitter, Bell tells her that he and CJ will be moving to Wales, much to Maddie's excitement, but when Bell realises CJ is against the idea and that he should be a priority, he decides to stay at Elmsmere, and in the Carter flat too, much to Maddie's dismay. In Prizes, he once again promises to move out but decides to stay in the flat after learning about friendship, much to Maddie's dismay again.
In AXOLOTL, it is revealed that both Mr Boyd and Miss Harper have left, Miss Harper left to a better school. It is unknown about Mr Boyd. Bell is upset so he bans staff relationships, much to new music teacher Clinton's dismay who is dating WPC Rowe, Elmsmere's police liaison. Jack has likely moved out too. CJ did not appear in this episode either and it is very much possible he has moved back in with his mum and stepdad but this may not be the case yet and he may just not have had a reason to appear in this episode.