Macht describes his character as more than an attorney, but a "power manager". "He doesn't take anything too seriously, except power", Macht stated during an interview with Soap Opera Digest.
Trevor's dynamic with his love affair, Kate Howard (Megan Ward), displays quite an unusual dynamic. Macht revealed that though his character would love to get back together with her, he mistreats her because of her involvement with his "step-son", Sonny Corinthos (Maurice Benard), and his pride is hurt; he has lost yet another woman to Sonny.
Trevor's hate for Sonny stems from Adela's decision to choose Sonny over him and their son, Ric (Rick Hearst). When Adela dies, it destroys Trevor's faith in love and drives a wedge between him and Ric.
The character of Trevor Lansing is first introduced to the audience in 2003 through his son Ric Lansing, when Ric reveals to Sonny Corinthos that he and Sonny are half-brothers. After Sonny's father Mike walked out on Sonny and his mother Adela, Adela began an affair with Trevor, who was married at the time, and became pregnant with Ric. She was his secretary. He sent her to live in his vacation home in Martha's Vineyard.
Sometime during the pregnancy, Adela fell down the stairs while trying to get little Sonny to wear a jacket. Trevor blamed Sonny for the accident and told Ric that Sonny was so jealous that he pushed his mother down the stairs. Soon after Adela gave birth to Ric, Trevor gave Adela an ultimatum: put Sonny up for adoption, or give up Trevor and the new baby. Adela chose Sonny and walked out on both Trevor and Ric's lives. Adela was later killed by her future abusive husband Deke Woods.
On August 22, 2007, Trevor arrives in Port Charles. He is an attorney and the former lover of fashion mogul Kate Howard. After Kate tells Trevor about her pending legal woes, Trevor reveals that Ric, the prosecutor pursuing the case against Kate, is his son and promises Kate that he will get Ric off her back. He calls his son "a disappointment.". Sonny, who is now Kate's lover, sees Trevor as a major threat in light of Trevor's connections to Ric and Kate as well as with Anthony Zacchara, who is ostensibly the most powerful mob boss in Manhattan.
Indeed, on October 22, 2007, it comes out that Anthony Zacchara has been insane for years and that it is Trevor who has secretly been the actual head of the organization. Trevor puts a hit on Sonny but it fails. He is still very much in love with Kate Howard, and hates her being with Sonny.
Trevor now works for crazy man Anthony Zacchara and is keeping a wary watch over his children, Johnny and Claudia. Johnny and Claudia hate Trevor and blame him for a lot of their pain and anger toward their father. Trevor has always had a pained relationship with his son, Ric.
On March 22, 2008, Ric confronts his father about all the pain that he caused him in the past years when Trevor comes for the deeds to the waterfront. Trevor just ignores Ric's pain and asks for the waterfront deeds again. Ric gives them to him, walks over to the fireplace, and breaks down. Trevor silently exits with Ric watching him leave. It is revealed on July 7, 2008 that Trevor raped, seduced, and slept with Claudia Zacchara when she was a teenager. When Anthony walked in, he then shipped Claudia away for sleeping with him.
Trevor and Sonny are injured in the explosion of February 9, 2009. Sonny was going to shoot Trevor after he threatens to drop the biotoxin, which causes everyone in Port Charles to get sick. In a confrontation with Sam McCall on the roof, Trevor tosses the toxin and Sam tries to catch it. Trevor's attempt to stop her results in him falling off the roof, resulting in his death, as confirmed by the F.B.I.
Adultery; had an affair with Adela Corinthos while he was married [Pre-1974]
Statutory rape; had sex with a 16-year-old Claudia Zacchara [Revealed Jul 7, 2008]
Various mob-related crimes while running the Zacchara mob empire