Presumably, Hal and Betty had a good relationship before elder sister Polly began dating Jason Blossom. During her childhood, Hal and Betty would fix cars together, a skill that came in handy when she and Veronica broke in Ms. Grundy's car.
When Jason Blossom's corpse was found washed up on the shores of Sweetwater River, Alice, Hal and Betty stood by and watched as the body was brought to land.
The morning after Jason's body was found, Alice and Hal informed Betty that due to the scandal surrounding his death, they'd be having a lot of late nights at the local newspaper they ran together, The Register. No one cared about an accidental drowning, but the murder of the sociopathic son of the wealthiest family in town was bound to make headlines.
Days later, Hal and Alice knocked on the door of the Andrews house. Hal first apologized to Fred Andrews for coming unannounced, but it had been a rough couple months for them. Before Hal could finish his sentence, Alice cut him off, she insisted that Archie Andrews and Betty stop spending time together. She claimed the relationship was toxic, on both sides, and their recent behavior reflected that.
While Alice was away at a women and journalism spa retreat, Hal took the opportunity to work on his car, and was joined by Betty who wanted to talk about Polly. Hal explained that Polly and Jason had had a fight, he was unsure what the fight was about, but Polly was devastated afterwards. He claimed to have come home from work one day to find Polly attempting to commit suicide, which was why she was sent away. Later that night, Betty spied on Hal as he watched old home movies of Polly, while drinking his sorrows away.
Hal later attended Jason Blossom's Memorial, where he had a run-in with Cliff Blossom, they had a brief heated exchange of words, seen by Betty, and went their separate ways. Once home, after Betty had been told by Rose Blossom, Betty confronted her father him with news that Polly had been engaged to Jason, however, Hal was already aware of the engagement. Betty wondered if that was what he and Cliff had been arguing about. Hal denied it and explained that their argument was about their families, and the fact that the Blossom clan came extremely close to destroying his family. Cheryl's great-grandfather murdered his grandfather over money. They had been business partners in selling and trading maple, but one day, Cheryl's great-grandfather decided that he no longer wanted to share the profits, so he murdered Hal's grandfather. The Blossoms stole their livelihood, and Hal would die before he'd allow them to steal his daughter too. Jason made her sick, so she would not be returning home until she was no longer sick. He warned Betty to stay out of it.
As she discussed the matter at school with Jughead, Betty had come to the conclusion that Hal was the culprit that broke into Sheriff Keller's house while everyone was at the drive-in on closing night and stole the evidence regarding Jason Blossom's death. Jughead then questioned how far exactly Hal would go to protect Polly, before adding the Coopers name to their murder board.
Having learned that Betty and Jughead secretly visited Polly at the Sisters of Quiet Mercy, and discovered her pregnancy, he questioned if Betty had found what she was looking for while she was there. Much to her disappointment, she didn't. However, that didn't stop Hal from being the target of Betty's suspicions. He hated the Blossom family for stealing the Cooper family legacy, as well as Polly being pregnant with Jason's child, which gave Hal motive. She accused her father of not only breaking into Sheriff Keller's house, and stealing the files on Jason's murder, but possibly being the murderer. Alice laughed hysterically at the notion that Hal could be Jason Blossom's killer. She claimed he didn't have the stomach for it, though she wished he had done it, or that she had done it, as Jason deserved it after what he did to Polly. Hal and Alice accused Betty of sounding just as crazy as Polly, who Hal claimed was distressed and delusional, and her story about running off with Jason, just a fantasy. However, Betty didn't believe them. Alice then told Betty that she may not believe them when they said Polly was crazy, but she would obey them.
Hal was a part of a search party to find Polly, which had been organized by Betty and Jughead, encompassing the eastern part of Eversgreen Forest, the most likely direction Polly would have gone if she was attempting to leave Riverdale unnoticed. During their search, the Coopers had a heated argument with the Blossom family, who were leading a search of their own. Penelope Blossom accused the Coopers of hiding Polly, a potential suspect in Jason's murder. Since the search was ultimately unsuccessful and to get ahead of the suspicions, Alice was forced to come forward. She held a press conference and dismissed all the negative rumours and announced that Polly was pregnant with Jason's child.
At breakfast the next morning, Betty questioned if Polly could return home since everyone was now aware of her pregnancy, to which Hal and Alice said yes. Betty then asked where the baby would sleep and Alice claimed that Polly had decided to give the child up for adoption. Hal firmly stated that that was her only option, unaware that Betty had secretly found Polly the night before, hidden in the attic, and knew her sister wanted to keep her child. Unable to live at home, Betty arranged for Polly to stay with Veronica Lodge and her mother.
After Alice kicked Hal out of the Cooper house for secretly making Polly and appointment to receive an abortion before she had been sent away, they reunited when Alice arrived at The Riverdale Register with Betty where they presented him with a USB flash drive that contained a tell-all exposé of the corruption surrounding the Blossom family. With motive and the capacity to see it through, Alice and Betty decided it was time for the Blossoms to answer for all the harm they had caused, everything up to and including them taking Polly, who was currently residing at Thornhill. However, Hal refused to publish Alice's article as it would only serve her personal vendetta against the family. Having been bitter after getting kicked out of the house, Hal changed the login password for the Registers' computer, in preparation that the day would come when Alice would require it's service. He explained that he was kicking her out of the Register just as she kicked him out of their home and that she was fired. Alice and Betty left, but Alice was so consumed with anger, she shouted that she wanted her daughter back, and threw a large rock through the shop's door, shattering the glass, much to Hal and Betty's shock.
Betty was greeted by her father and mother as she returned home from school that evening. Hal told Betty that the envelope that she had brought in earlier that morning from the front porch was "fan mail" from the shooter, who was calling himself the Black Hood. He wanted them to publish his letter claiming responsibility for the shootings of Fred Andrews, Moose Mason, and Midge Klump, as well as the murder of Geraldine Grundy in Greendale. As proof that he is who he says he is and that the letter is from the actual killer, inside the envelope was Fred's missing wallet and Geraldine's glasses.
The next day, Hal and Alice were approached by Betty and Polly, who after reading their published article of the Black Hood's letter in the Register, decided that she would be leaving Riverdale for her own safety. She had already made arrangements at the Farm. What Farm, Alice wondered. Polly explained that she was referring to the very same Farm that she and Jason had planned to run off to before he was murdered. Hal suggested that Polly settle down, so that they can talk about what to do next. Polly was worried about her well being, as well as the well being of her unborn babies. With the killer targeting sinners, she was no longer safe in Riverdale considering that she was an unwed mother carrying her cousin's babies. Over Alice's dead body would she allow Polly to run off and give birth at a Farm, though she didn't have much say in the matter as Polly had already made up her mind. She stormed off, with Hal not far behind, hoping to talk some sense into her.
Hal and Alice confronted Betty after learning that Poll had left town despite the fact that she had told her not to. They sat Betty down at the dinning room table because she had let Polly go without alerting her Alice. When Betty tried to justify her actions for helping her sister, Alice burst into tears, revealing how she was constantly terrified for her daughters' safety knowing there was a killer on the loose. Every time Betty walked out the door or didn't answer her phone when she called, Alice worried that something terrible had happened to her. It was the acts that she and Polly did in secrecy that made it difficult for their mother to protect them. They even label Alice as a monster for trying to protect them. This upset Alice to the point where she left the room, leaving Hal and Alice to cope with the revelation.
Two days had passed since their discussion with Betty, and so Hal and Alice attended the Town Hall meeting, where Mayor McCoy welcomed all to the event in hopes that she could address their concerns and if possible, ease their minds, as she too shared their desire to protect their town and their children. Mayor McCoy and Sheriff Keller then announced the introduction of a town-wide curfew and helpline that residents can call to report any suspicious activity. Alice questioned the legitimacy of the so-called helpline, connecting it to the Red Circle. She was wondering when they were going to address the real problem in Riverdale, which is the south side. This resulted in a heavy debate between her and Fred as the two argued over how best to handle the problem, which only came to an end after Betty and Jughead interrupted the meeting to announce the supposed arrival of the Black Hood.
Shortly after, the Town Hall meeting brought to an abrupt end, Hal, Alice, Betty, Jughead, Sheriff Keller, and Mayor McCoy reconvened at the Cooper's house, where they hoped to gain a better understand of how Betty and Jughead knew where the Black Hood would strike next. Betty handed them the letter, which was sent to her by the Black Hood, along with the cipher that she had earlier turned over to Alice, revealing that she had withheld evidence from them in an attempt to solve the cipher herself.
Hal was furious with Betty after learning that she published an archived article at the Blue and Gold of Alice's arrest from many years ago, when she was a young member of the Southside Serpents. He couldn't comprehend why Betty would do such a thing. Alice explained that it was revenge, though Betty claimed that it was justice against her and her holier-than-thou attitude.
After receiving news from Tom Keller, informing Hal on Betty breaking into his home, Hal was called down to the Sheriff Station, where he was seated next to Betty, while they had a chat with Sheriff Keller. As he informed Hal that Betty had an overly active imagination, where she was painting a picture of him being the Black Hood. Later admitting, while stating to Betty the fact, that even though she was completely wrong about her theory, he understood why she would think of him being the Black Hood. Later handing her his journal on his investigation of the Black Hood. After handing the journal over to her, he assured Betty that he wouldn't say a word to Kevin about what she did. Stating that it would break his heart, later telling Betty the reason why he decided not to tell Kevin about her recent activities, was because she was there for him when he needed her the most.
Hal briefly appeared in Betty's anxiety induced nightmare along with Alice and Polly. The three of them gathered in the living room by the fire place, as Betty came down the steps. They wished her a Merry Christmas. Moments later, Hal was dead, as were Alice and Polly. In Betty's nightmare, they had been murdered by the Black Hood.
In reality, on the night of Christmas Eve, Hal and Fred were called down to Pop's by Sheriff Keller after Betty and Archie were attacked by the Black Hood. Fortunately, the Sheriff managed to kill the Black Hood before he could escape.
Hal and Alice learned from Betty that Polly gave birth to the twins at the Farm. As Hal tried to cope with the news, Alice struggled to hold back her tears. Hal questioned why Polly hadn't informed them of this. Alice surmised that Polly didn't want them to be apart of the babies' lives. Alice then asked Betty if Polly was alright and if the children were healthy. Betty reassured her, stating that Polly is fine and the babies are healthy. Betty revealed that this wasn't all she had to share. After some digging, she found an address for Alice's son and her biological brother, that was given up for adoption many years ago. His name was Charles Smith. With Polly gone, Betty assumed that this would better their lives, but Hal would beg to differ. He scolded Betty for prying into something that had nothing to do with her or Polly. Betty exclaimed that she did it for her mother, though she was clearly upset by the recent revelation, Alice agreed with Hal, deciding then that it was best to end the conversation.
The following evening, as Hal and Alice sat in the living room, reading books, Betty returned home with Chic hanging over her shoulder. She called out to them for help as Chic's arm had been sliced open. Hal, Alice and Betty took Chic to the kitchen, where they grabbed the first aid kit and applied medical care.
At the breakfast table with Alice, Betty and Chic, Hal began an intrusive line of questioning, starting with how long Chic planned on staying with them. Alice stated that he was free to stay for as long as he wanted to. Hal claimed that he was simply trying to plan his life. When Betty brought Chic home, he was bleeding profusely from his arm. Hal sought answers on why Chic was in that condition. Betty told Chic that he didn't have to answer her father's questions but he did so regardless. Chic's attacker's name was Marcel. He ran the Hostel, and sometimes, he booked clients for them. The night Betty showed up, Chic wasn't in the mood to work, but Marcel attempted to convince him otherwise. Both Hal and Betty both expressed interest in the type of clients Chic catered to. Chic replied that he had clients ranging from nice to even nastier than Marcel. If Hal preferred, Chic could specify, along with showing him a decent collection of scars that he had acquired over time. Betty also had scars, crescent marks in her palms, from digging her nails in them. Like Betty, Chic once dug his nails into the palms of his hands.
Despite claiming that he was staying home to catch up on a few odd jobs around the house, Hal confronted Chic at Pickens Day. He asked if Alice knew what kind of person they had welcomed into their home, in the room next to Betty's no less. While they were gone, Hal gained access to Chic's computer. In doing so, he discovered what Chic had been doing online with his "clients". Betty insisted that he stop snooping through Chic's business and harassing him, though Chic wasn't the only subject of Hal's anger. He even scolded Betty for bringing Chic into their lives and into their home, more specifically, Polly's bedroom. Alice remarked that Polly was no longer apart of their lives and that therefore, it was no longer her room. Hal insisted that Chic had to go and that Alice knew exactly why. Alice reminded Hal that she had thrown him out the house before and that she would not hesitate to do it again. Heading the warning, Hal took off.
As he stood by the front door, holding a suitcase, Hal gave Alice an ultimatum, either Chic goes or he goes, though Alice wasn't willing to entertain his insane notion. She and Betty tried to explain to Hal that Chic wasn't hurting anyone and that he had found a job at the Bijou. He had even offered to pay them rent. So Alice had no idea what was Hal's beef with him. Hal replied that Chic was a stranger, though Hal wasn't even making an effort to get to know him. However, he refused to change his stance on the matter. Before leaving, he told Alice and Betty to call him once Chic was gone. In the meantime, he'd be at a ShareBNB down by the Register.
In the late hours of the night, Hal stopped by the house for toiletries though he made a point to call Betty first to alert her of his arrival as he didn't wish to get into a fight with Alice about Chic who was in his room resting. He entered the house to the strong aroma of bleach. Alice supposedly spilled tomato soup on the rug and she didn't want it to stain. After remarking that it must've been a lot of soup given that the house smelled like a hospital, Hal headed upstairs to get the toiletries he had come for.
Later that week, Hal returned home. He was greeted by Chic who told him that neither Betty nor Alice were home at the moment. Nonetheless, Hal pushed his way through the door to remind Chic that it was still his house after all. Betty arrived at the house soon thereafter to find Chic frantically pacing back and forth in the dinning room as Hal accused him of stealing his grandfather's watch and running some kind of scheme. When Betty asked what he was doing home, Hal told her that he had a change of heart and he was feeling that it was time for him to move back in and more importantly, get some answers from Chic. Hal questioned everyone's strange behavior as of late. He asked why the house smelled of bleach, what happened to the dinning room rug and where the lamp went. He was certain that something was going on in the house and that it involved Chic, who was possibly turning tricks and pawning their valuables. Betty demanded that Hal get away from Chic and leave the house or else she'd tell Alice about his affair with Penelope Blossom. Maybe the reason he felt like they were hiding things and keeping secrets is because he was. Out of fear that Betty would follow through with her threats, Hal left the house.
It had been a long time coming but it was time when Hal decided to sit down with Alice, and ask for a divorce. Betty was there as well. Alice asked if he was still seeing Penelope Blossom. Which he wasn't. Furthermore, the divorce had little to nothing to do with Penelope. Hal explained that it was about how he worshiped Alice like a goddess for 20 years only for her to side with Chic, a stranger, over him. Betty too. He couldn't believe that they chose Chic. However, Betty claimed that she was on Hal's side in regards to Chic. She too wanted him out of the house. As for selling the Register, he explained that Hiram Lodge offered a fair price, half of which he was willing to give to Alice as long as she was willing to agree to set him free immediately. Little did Alice know, Hal's sudden want for a divorce had something to do with Clifford Blossoms' upcoming will-reading.
The next day, Hal, Betty and Polly attended the will-reading at Thistlehouse. Also in attendance was Cheryl, Penelope, Nana Rose and Toni. In the will, Clifford's first declaration was that ownership of Thistlehouse remain with his mother, Nana Rose. With Penelope, Clifford left ownership of Thornhill, which Cheryl had burned to the ground. Any and all remaining assets of Clifford's fortune was to be divided in half. The first half would be distributed equally to anyone in town who could prove with medical authentication that they were of Blossom blood. The will-reading was then interrupted by Alice who came to confront Hal over him asking for a divorce for the sole purpose of cutting her out of the will. This led to a confrontation between Alice and Penelope. After Alice was escorted from the premises, the will reading continued. The second half of Clifford's assets were to go to his true heirs, Cheryl and the now deceased Jason. As Cheryl gave a speech, Clifford's twin brother, Claudius Blossom interrupted the will-reading.