Jack is Liam's older brother. He was first seen in the Series 3 episode 'Big Brother.' He first met Liam when he was working at an pirate DVD store. When he refuses to give Liam his money back, Liam kicks over his stall and he chases after him. Jack then witnesses Liam getting arrested when he tried to help a woman with her things but she thought he was stealing them, but says nothing.
When he has to leave, Tracy takes a picture of him with her iPhone and later shows Liam, where he realises his brother was the pirate DVD stall owner. He then breaks his curfew to go and see him but he is arrested. At the police station he reveals that he is actually an undercover cop bringing down the DVD company and that he wanted to give his statement but couldn't because it would blow his cover. He did do in the end which was enough information to let Liam go free. He has now fostered Liam.