Steve Trevor was a U.S. spy during World War II and the one-time lover of Wonder Woman.
Steve Trevor was an intelligence agent of the U.S. Government assigned to work in war-torn Europe during the Second World War.
After obtaining evidence of an upcoming invasion of Britain, Trevor had to get the information to France. He stole an aircraft off a Luftwaffe base, but after a short dogfight, he was downed. Knocked out by debris, he plummeted to the ground. Mere seconds before meeting his end, Wonder Woman saved Trevor. Thinking himself dead, he referred to her as "Angel", and though she claimed he was still alive, seeing a strange green man made him seriously doubt that.
Trevor had to meet up with Ernst, a code breaker, who could help him with a communicator. Ernst wasn't at the rendezvous point, so Steve and Diana had some time to get further acquainted. The meeting point was set up, however: German troops attacked the villa. Trevor heroically offered to fight them off and went outside with his revolver. He found Diana to be much stronger; by the time he had reloaded, she had broken the siege herself.
Wonder Woman interrogated a captured soldier and learnt where Ernst was held. They tried to save him, but found that the prison was set up too. Seeing as the Germans were after the communicator, Diana made sure they found only part of it in the rubble that resulted from the attack. Satisfied, the Germans pulled back. Ernst started working on decoding the communicator learnt that the true target was not Britain, but America. Wonder Woman took off in attempt to stop them. Steve made his own way out, sadly believing to have lost his "Angel" forever.
Many decades later, when Steve was living in a retirement home, Wonder Woman came to visit. He recognized her and they both watched the sunset together.
Steve Trevor was Wonder Woman's love interest in the comics. A fighter pilot downed above Paradise Island, Diana had to escort him back.