By the time he was an adult, Orson had become a dentist. He was set up by his mother and his girlfriend to get married when he got her pregnant. Alma miscarried and Orson never came to love her and began an affair himself with Monique Pollier. When Alma found out she decided to punish him by faking her own death. However since there was no body and no evidence (a panicked Orson had cleaned everything up), he never went in jail. Yet Alma's friend Carolyn Bigsby became his arch nemesis, accusing him of killing his wife. Free, he tried to begin a new life with Monique but found her dead, with his mother saying it was an accident when she had in fact killed Monique to punish Orson for cheating on Alma. He had to hide the body when Mike Delfino, whom Monique had called, came to do some plumbing. Gloria convinces a reluctant Orson to aid her in covering up the murder. The mother and son bury Monique at the country club, his mother having removed Monique's teeth to prevent identification. All of this would soon come to haunt him. Orson meets Susan at a movie theater and helped her get Mike jealous. He then met Bree Hodge, who was residing at the hospital he stayed in during his youth. When Bree sees Orson visiting an old friend at the hospital, the two are instantly attracted to each other. Their relationship is furthered when Orson helps Bree escape from the hospital so she can be with her daughter Danielle. However, when Mike sees Orson for a dental exam and recognizes him, Orson runs over Mike with his car in attempt to cover his tracks, subsequently putting Mike in a coma.
After six months of dating, Orson proposed to Bree, who accepted. Mike, though alive, wasn't a threat anymore as he had a retrograde memory loss from his coma. Unfortunately for them Carolyn eventually returned. They still got married, even though Bree had to ask him if he hadn't killed his wife first. They were about to go on their honeymoon, but canceled at the last minute when Bree saw Andrew Van de Kamp on TV and decided to go after him, only to be rejected. Orson ultimately talked him into coming back, making him realize he would hurt himself just as much as his mother otherwise. Orson told Bree that Carolyn's husband had an affair which ultimately led to Carolyn holding several people hostage (including Edie, Julie, Lynette, Austin and Nora) and killing Nora.
She then tried to reunite Orson with his family, by finding his mother who was revealed to not be senile, as he had told Bree. This backfired when Gloria tried to drive Bree away from Orson by revealing he also has an affair with Monique, but Mike Delfino's arrest cleared her suspicions for the time being. This, however, turned Susan into Orson's arch nemesis. Gloria then had Alma, who wasn't dead after all, come and try to get Orson back herself. She tried to "repair" her miscarriage by drugging and raping him; she faked suicide to have him come to his home unsuspecting. Bree sided with her husband, leading Gloria to sabotage her ladder, making her land at the hospital. Andrew, who thought he was the culprit since he had partly eavesdropped his confession to Bree, threatened him to meet "bad Andrew" and Mike, whose bail had been paid by Zach Young, then began to remember the night of Monique's murder. He confronted Orson on the top of the hospital where he visited Bree, accidentally pushing him from the roof.
Bree and Susan reconciled after her accident and Orson used Alma's well-timed death, her suicide letter and his mother's stroke to implicate them in Monique Pollier's murder, clearing Mike's name at the same time. Orson visited his mother and banished her from his life, and he and Bree departed to their honeymoon, though not before sending a pregnant Danielle to a convent to avoid scandal. When they returned, it was revealed that Bree had faked her pregnancy and they would raise the child as their own.
This proved to not be that easy as they had to prevent anybody from touching Bree's belly and even once make up a story to explain why a fork had entered Bree's belly without her noticing. They also had to deal with genuinely pregnant Susan who wanted to go to Bree's ob-gyn and Danielle's various trouble, even endangering her baby's life by rollerblading. Although Orson wanted to throw the towel, he decided to continue to pretend his wife was pregnant when a teary-eyed Bree told him this baby was her second chance at parenting. They have appeared to be successful as only Phyllis Van de Kamp and Adam Mayfair have found out and both have agreed to keep the secret, although before that they had to foil Phyllis's ploy to get back at Bree by having Danielle stay and raise the child with Phyllis by using Danielle's craving for fun.
Danielle gave birth to a baby boy on Halloween. After a tearful goodbye, Danielle handed her baby over to her mother. Bree and Orson named the baby Benjamin. When Bree wanted to get the baby circumcised, Orson was opposed due to foul memories of his own circumcision. However, Bree went through with it behind Orson's back. Orson was angry when he found out but he hesitantly forgave Bree and let it go, though it was clear that there were lingering resentments. After a tornado, Orson, Bree and Benjamin all move into Susan's house and Orson begins sleepwalking. When Julie comes in late one night, she finds Orson and he unconsciously says "I'm sorry I ran you over, Mike". Julie later told this to Mike, and he forgave Orson. Everything turns when Mike tells Susan about this, and the next minute she barges into Bree's house, angry at Orson telling him not to come near her family again. Bree found it impossible to forgive him, kicking him out of the house. He stayed briefly with Edie, as well as living for a while in the Fairview Towers apartment complex.
At the conclusion of the season Orson once again urges Bree to forgive him - only to be rejected once more. She tells Orson that the only way their marriage can be saved is if he turns himself in to the police, which Orson is unwilling to do.