Named after her loud, wayward grandmother, Little Mo couldn't have been more opposite. She was a very 'mousy' character, often shy, and immensely kind-hearted through all the pain she went through.
Trevor eventually made her become more isolated from her family and raped her on the bathroom floor when she told him she was going to her sister, Lynne's, wedding. On Christmas Day, Trevor shoved Mo's face in her Christmas dinner and made her eat it off the floor, a scene which attracted huge controversy and complaints from viewers.
On New Year's Eve, timid 'doormat' Little Mo broke out of her shell and attacked Trevor, bashing him repeatedly around the head with an iron when he prepared to attack her. She initially thought he'd died and when she and her sisters returned home, he had gone, with only blood on the door handle as a sign. Mo was prosecuted and imprisoned for attempted murder, released on appeal. Trevor terrorised Mo after she managed to move on and planned to divorce him, but he took her hostage in her house, which accidentally set on fire. Fireman Tom Banks saved Mo, and when he went back in to get Trevor, they were both burned alive.
After almost a year of happiness, her friend and her father's darts-playing buddy, Graham Foster, raped her at night in The Queen Vic while they were alone after hours. She told her family, and her dad, Charlie, promptly battered him, although he faced paying compensation. Mo discovered that she was pregnant with Graham's baby, and much to Billy's shock and disgust, she refused to abort the child, stating that she's always wanted children and the unborn baby didn't ask to be brought into the world this way. She and Billy split up, and Mo went away to give birth. She named her baby Frederick (Freddie for short), after her grandfather and gave him the middle name of William, telling Billy when she saw him that she wanted to give him the names of good men. She and Billy decided to give things another go, but Billy admitted that he didn't love Freddie as his own and couldn't help his feelings. They separated and divorced but remained very good friends.
Following her relationship with Billy, Little Mo continued with the task of bringing up her baby as a single mother. She fell in love with Alfie Moon, the estranged husband of her sister Kat Moon. This relationship failed once Little Mo discovered that Alfie had secretly been dating Kat behind her back, and Alfie and Kat left together to start a new life.
Since February 2006, it has been observed that Little Mo is having some difficulty caring for her child. Mo reports that Freddie is teething, but refuses to medicate him, and has exceptional trouble "getting him to sleep". Freddie recently sustained a head wound as a result of a fight with Bobby Beale, and this resulted in a visit from the health visitor. Little Mo interpreted this as questioning her parenting ability and was extremely hostile to the health visitor. Little Mo was also constantly taking Freddie to see Dr. Oliver Cousins, who later said he could no longer be her GP because he was interested in her romantically. The pair started dating in April 2006.
Her anger at the social services made her piece together that Ben Mitchell was the one that hurt Freddie. She confronted Ben at the Vic and shook him violently. The Mitchell clan were warning Mo not to come near Ben and she nearly lost her job at the Vic. However her father managed to persuade Peggy not to fire her. On May 8, 2006 Mo returned to the Vic but had to listen to Phil and Grant's constant warnings. Eventually she and Ben saw each other and he ran away, this resulted in Peggy firing her. She tried to convince everyone that Ben was the one that hit Freddie. Her hopes and trust from her father were dashed when he did not support her. Soon Charlie believed her and begged her forgiveness for doubting her.
After extensive tests at the hospital, it was discovered that Freddie had a temporary low platelet count, due to an infection, meaning that any minor injury could hurt him badly, as his blood wasn't clotting properly. Mo was no longer suspected of hurting her son. Though she was cleared by the hospital and the police, she was still under suspicion by the residents of the Square. Their suspicion of her was confirmed when Ian Beale became uncomfortable when she was about to hold Bobby. Knowing that people would still suspect her she made the decision to leave the square on May 18, 2006. The next day Ben Mitchell confessed to Phil that he accidentally dropped Freddie whilst they were playing horsey. Mo was confused as to what she should do. Phil in the mean time was trying to convince Mo not to go the police, which she eventually didn't. Oliver also tried to convince her to clear her name but she refused to back down from her decision. This led to an outburst in the Vic when Peggy called Mo a child beater. Oliver tried to defend Mo but she ended up storming out the Vic, angered by the fact that Oliver did not respect her decision.
Mo prepared to leave for Barnstaple and just as she reached the station, Oliver, who was also about to leave for Leeds, tried to convince her one last time that they could be together. Mo made her choice and decided not to join him. She said that all her life she was doing what she was told to do and now she wanted to break away from being "Little" Mo. She gave Oliver one last kiss and left, after saying how she would keep in contact and travel to Leeds to visit him. As she left Walford she looked at Freddie and said, "It's just you and me now," with a smile on her face.