On the first episode of the fourth season it is revealed that Edie didn't intend to actually die, she had knocked over the chair which was keeping her up and held onto the bar above, and waited until Carlos would arrive. When he does to collect his stuff Edie lets go of the pole and starts to hang. Just then Karen asks to speak to Carlos about the garbage and while he goes to talk to her Edie is upstairs hanging, and Karen notices it from the window and Carlos runs up to save her. Edie survives and uses this as an excuse for Carlos to stay with her and when she returns to the street she is welcomed back by Gabrielle, Susan, Bree and Lynette and soon she learns about Carlos' secret bank account and she secretly uses it against him saying he knows he can trust her and she knows she can trust him, while Carlos is having an affair with his ex-wife Gabrielle. She says, "You can trust me with your secrets, just as I can trust you not to hurt me." She uses her recent suicide attempt to guilt and trick Carlos into staying with her, and he desperately tries to be with Gabrielle. In the second episode of the fourth season "Smiles of a Summer Night" Edie pushes Carlos too far such as blackmailing him a bit further and even asking him to marry him and says to him that if he was to say no she would let it slip about his illegal bank account, Carlos says yes however at the end of the episode it's revealed that Carlos is paying someone to stop Edie from runining his life. Most likely paying someone to kill her.
After the loss of the baby, Carlos managed an early parole by seeking aid from a program designed for Catholic inmates. Through the program, Carlos made the acquaintance of a nun by the name of Sister Mary Bernard, who has inspired him to live a more religious life. This invoked the jealousy of Gabrielle, because the Sister is "a knockout", by Gabrielle's admission, and also because she seems to be convincing Carlos to resent Gabrielle. Sister Mary had invited Carlos to accompany her to Botswana, and he accepted at first. When he went to the doctor for his physical examination and vaccinations in preparation for the trip, he left Gabrielle to finish the questionnaire for him, on which she neglected to mention his allergy to eggs, instead, telling the nurse that he was allergic to fish eggs (caviar). This resulted in Carlos becoming sick from an allergic reaction caused by one of the vaccines, forcing him to stay home with Gabrielle. In the season finale, Gabrielle believed Carlos to be dead but soon discovered he paid the gardener, Ralph to do his community service instead. Ralph was hit by a car. Gabrielle also discovered that Carlos was having an affair with the maid, Xiao-Mei (who was carrying Carlos's and Gabrielle's child).
In the third season opener, Gabrielle tells Carlos that she wants a divorce. At Bree & Orson's wedding party, Xiao-Mei's water breaks. The baby is born black and the doctor tells Carlos & Gabrielle that the wrong baby was put in Xiao-Mei. Carlos and Gabrielle do not get to have their child making their divorce easier. After battling things out with Gabrielle for a while, going through a nasty divorce, Carlos and Gabrielle, during the hostage situation, come to terms that they do not wish to be the rage-filled, vengeful, bitter, schemers that the divorce had turned them into, any longer. Carlos's attempt to stop scheming clearly had limited success. Carlos moved in with Mike Delfino, claiming to have been his best friend before Mike was hit by Orson Hodge. Although it is possible that Carlos and Mike were close before the accident, there was not much evidence of this in the first two seasons, and taking advantage of Mike's amnesia would be perfectly consistent with Carlos's past actions. He has also began dating again although he and Gaby still have strong feelings for each other. Carlos tells Gaby that he's right across the street if she ever needs him.He later bonds with Travers McLain and then Edie Britt which reignites his need for children. Not long afterwards, Edie, having hit a dry spell in her love life, conspires with Travers to lure Carlos over to her house late in the evening so that Edie can make a move on him. Carlos judges Edie for using her son as "sex bait", and Edie gets upset by this. Later Carlos apologizes, saying he had no right to say it. Edie tells him that she's changed and strips in front of him, revealing her body's imperfections and showing a vulnerable side of her personality that she normally keeps hidden. When she's finished, Carlos hugs her, and later in the episode, Edie and Carlos are in bed together. Carlos and Edie awaken after having sex, both feeling awkward at how bad the sex was between them. Edie makes an excuse and tries to leave as early as she can. Later that day, Travers asks Edie if she was bad in bed, because he heard Carlos telling someone that on the phone. Edie confronts him and they reveal how bad they thought one another was, and they have sex for a second time. Things go worse and both Edie and Carlos have to go to the hospital when they sustain injuries. They agree to stay friends. Travers, Edie and Carlos spend the day together at the Zoo and when looking at pictures, they comment on how they look like a good family. They share an emotional moment together and Carlos kisses Edie, and they finally have good sex with each other, and their relationship hit a new level.
Carlos and Edie continue to have sexual relations but they fear being caught, and are nearly caught out by Mike. Edie uses her position as a realtor to use empty houses for their advantage. However, when Carlos reveals he doesn't want Gabby to find out, Edie is convinced he's still in love with her and puts an end to their relationship. Edie announces to Gabrielle at her engagement party that she's been dating Carlos, which doesn't go down too well. Gabby puts a smile on for the rest of the night but continues to be bothered about it underneath. She then confronts Edie and tells her she's not happy with it, but Edie refuses to stop seeing him. Gabrielle begins to put school girl tactics in motion to get back at her, and tells Lynette and Susan not to speak to her. Edie retaliates by inviting both Lynette and Susan to Travers's birthday party. Both think Gabrielle is out with Victor all day, so she won't find out, but they panic when they see her car pulling up by the party. She says if they don't leave the party their friendships are over, so Carlos takes action and carries Gabby out of the party. She tells him she's in love with Victor, but he reveals to her he and Edie will never turn into anything serious. Gabby realizes he's still in love with her.Edie's ex-husband, Charles, comes to pick up Travers. Edie tries to get shared custody of Travers when she suspects Carlos might be losing interest in their relationship. Charles learns about this and he and Edie get into an argument. Edie threatens to hire a lawyer so she can get full custody of Travers. Carlos learns of Edie's plan and tells her that she should think of what's best for Travers which is for him to stay with Charles and not have to go back and forth. He comforts her, saying that he will be there for her and Edie decides to call off her lawyer.
Edie becomes upset when Carlos laughs at the idea of them getting married, when suggested by Mike. Edie asks Carlos if they can move in together but Carlos rejects the idea, having already signed a lease with the owner of Mike's house, Lillian Simms, who's in a nursing home. In an attempt to undo this, Edie visits Lillian and lies about Carlos to get her to rip up the lease, which she does. Under the law she can change her mind within 72 hours of the agreement, Carlos is evicted and Edie offers him a place to stay. Carlos catches on to the fact she has had something to do with this, and she asks him why he won't commit to her. He reveals he's not in love with her, and she tells him she might be pregnant. The pregnancy test comes back negative, and Carlos finds himself disappointed. Finding a new way to keep Carlos, Edie suggests they try having a child even though they're not in love, and Carlos agrees. Edie, however, is still secretly taking her birth control. Carlos eventually finds the birth control and dumps Edie, which leads her to attempt suicide in the finale of season three. After finding out that Victor only married her to gain goodwill, Gaby kisses Carlos of the day of her wedding.
In the fourth season, Carlos goes home and catches Edie, which turns out she faked her suicide attempt and when she kicked over the stall which held her on the ground she held onto the bars above, and when Carlos arrives in the house to collect his things Edie lets go of the bar, and Carlos is stopped by going into the room by Karen who yells at him about the garbage. She then notices something on Edie's bedroom window and Carlos realizes it's Edie hanging and he runs up and saves her and she's taken to hospital. Carlos rings Gabrielle on her wedding night and tells her that they can't run away from Victor and Edie like they planned too earlier in the day when they kissed and Gabrielle is annoyed. Edie uses her suicide and her knowledge of Carlos' illegal doings with the bank to save money to get him to stay with her, however he wants to be with Gabrielle. In the second episode of the fourth season "Smiles of a Summer Night" Edie pushes Carlos too far such as blackmailing him a bit further and even asking him to marry him and says to him that if he was to say no she would let it slip about his illegal bank account, Carlos says yes however at the end of the episode it's revealed that Carlos is paying someone to stop Edie from ruining his life. Most likely paying someone to kill her.