The conflict between Fiona Coyne and Tinsley Wharton began in Season 10 of Degrassi after Fiona caught her then boyfriend Bobby Beckonridge cheating on her with Tinsley at a school council event. However, when going to court over Bobby's abuse, Tinsley admitted under oath that Bobby abused her as well, which helped Fiona win her case. After Fiona won, she thanked Tinsley for her help. It is believed that the conflict was resolved as a result of Tinsley's testimony and Fiona's subsiquant win in court.
In What a Girl Wants (2), when Fiona wants to change the school uniforms and show her designs, Tinsley whispers in her father's ears and her father objects. However, Fiona's boyfriend Bobby uses his wits to outsmart Tinsley's father. Tinsley is shown to be jealous when Fiona and Bobby are kissing. Later, Fiona catches Bobby and Tinsley making out. Fiona confronts Bobby about it, and Bobby admits he that he used to date Tinsley, but she threw herself at him. However, Tinsley sends a text message to Bobby, saying she can't wait to see him, which makes Fiona upset.
In Try Honesty (1), Holly J. goes on to Declan's profile and finds pictures of him with Tinsley. She asks Fiona if she knows who Tinsley is, and Fiona calls Tinsley, "a slut" and "the one who [she] caught with Bobby with." They start seeing more pictures of Declan and Tinsley together, and Fiona reassures with Holly J. that Declan would never cheat on her.
In Chasing Pavements (1), Fiona watches a video of Bobby and Tinsley together. Then at the trail, Tinsley happens to be at Bobby's side to defend him. When Fiona tells Bobby that that no girl deserved to be abused, Tinsley looks at the ground, looking guilty. When Tinsely is questioned if Bobby has ever been violent, Tinsley reveals that when she and Bobby were at a party, she was talking to a guy, and Bobby didn't like it. They had an argument and then Bobby hit her. Later, Fiona wins her case and when she looks at Tinsley, she thanks her and Tinsley nods at her.