Lucas Gottesman was revealed to have been helping Mona with her “A” activities, but he was not a primary antagonist. He had a troubled time but eventually became a successful entrepreneur.
In the television series “Pretty Little Liars,” Lucas Gottesman is initially introduced as a friend of Hanna Marin. Throughout the series, his character undergoes significant development. Lucas was tormented by Alison DiLaurentis before her disappearance, which led to him having a grudge against her and those close to her. This grudge is what initially aligns him with Mona Vanderwaal, who is the original “A.”
Lucas assists Mona because he wants to get back at Alison and her friends for the way they treated him. However, he is not inherently malicious and his involvement with “A” is more a result of his own victimization and desire for revenge than a reflection of a villainous nature. As the series progresses, it becomes clear that Lucas is not a key player in the “A” team but rather someone who was manipulated into helping.
Later in the series, Lucas redeems himself. He becomes a successful entrepreneur and uses his wealth to help Hanna with her fashion career. He also admits to the Liars that he had been in contact with Charles DiLaurentis (CeCe Drake/Charlotte DiLaurentis) when they were younger, not knowing who she would become. Despite his past actions, Lucas is shown to be a supportive friend to Hanna and the others, proving that he has moved beyond his earlier mistakes. His character arc is one of redemption, showing that he has grown from the bullied teenager into a mature and successful adult who still cares for his friends.