Content Warning: This article contains discussions/references to death.
The flagship show of the CW's Arrowverse, Arrow is not known to be the most family-focused show. While the title characters of The Flash, Black Lightning, and Superman and Lois have always devoted lots of time and energy to staying connected with their families, the same cannot be said of the Arrow.
When Oliver Queen returned from "five years in hell" on Lian Yu, he spent a lot of time pushing away the people that he cared about in order to keep them safe from his mission and his inner darkness. It took a while for him to let people in, making the intentional family moments on Arrow arguably more special than on some of the other Arrowverse shows. And, while Oliver showed the most growth over the course of eight seasons, he wasn't the only character to learn the value of vulnerability.
Emiko Being Accepted By The Queens
In the pre-Crisis timeline, Emiko Adachi wanted desperately to be accepted as a member of the Queen family but never had the chance. She died helping Oliver fight the Ninth Circle after he acknowledged that they were family; their father was wrong to push her away and hide her existence from both of them.
When Oliver remade the universe after Crisis, he resurrected both Emiko and Moira Queen, which allowed them to finally rectify Robert Queen's mistake. Emiko meets Moira and Thea for the first time at Oliver's funeral. Thea calls Emiko her sister and Moira tells her that she is always welcome.
Oliver Becoming William's Dad
Oliver wasn't always the best father to William, partly due to the fact that he was unaware of his son's existence for many years. When Oliver got custody of William after his mother's death, he struggled to balance being the mayor and the Green Arrow with being a parent. But Oliver had made a promise to Samantha, William's mother, to take care of him and he intended to do his best to keep it.
At the end of the season 6 premiere, he stepped fully into his role as a father when he told William that he would always be there for him. William took a bit longer to warm up to Oliver, but it is in that scene that William starts to soften and accept Oliver into his life.
Sara Reuniting With Her Father
After her time in the League of Assassins, Sara thought she was too dark and damaged to be in her family's lives anymore. But, eventually, Sara chose to reveal to her father that she was still alive in order to protect him when the League was targeting her family. Sara and Quentin Lance's reunion is one of the most heartwarming scenes of season 2. They stand in the street, crying and embracing, before Sara explains her reason for being there. Even though her father didn't agree with many of her decisions, he tells her how proud he is of her for protecting people in their city.
Oliver and Diggle Calling Each Other "Brother"
There are so many amazing "bromance" moments between Oliver and Diggle that it is hard to point to just one, but the most memorable ones are when they support each other as brothers. In the season 1 finale, Diggle tells Oliver that "a soldier never lets a brother go into battle alone." Oliver reciprocates the sentiment in season 3 when he tells John, "You're the best man I've ever known. And whatever happens, you're my brother."
Through the years, no matter what these two faced and even when they were occasionally angry with one another, they always had each other's backs.
Moira Revealing She Knew Oliver Was The Arrow
Moira Queen was deeply involved in Malcolm Merlyn's Undertaking in season 1, essentially making her and the Arrow enemies. But, even though she once shot him, Oliver never bore a grudge against his mother. Towards the end of season 2, Oliver encourages Moira about her mayoral race and her strained relationship with Thea, citing his experience in making sacrifices for the greater good.
Moira then reveals to Oliver that she had figured out a long time ago, the night of the Undertaking, that he was the Arrow and she was proud of him for it. It was a beautiful moment, especially considering it was one of the last conversations Oliver would have with his mother before she was murdered.
Felicity Explaining Oliver's Mission To William
After William's mother died, Oliver and Felicity raised Oliver's son. Due to the demands of Oliver's job as mayor, his mission as the Green Arrow, and the time he eventually spent in prison, Felicity was the most present parent in William's life. Felicity looked after and loved William like her own son; she taught him about computers and helped him with his homework and science fair projects. As an adult, William even referred to Felicity as his mom.
William struggled to accept his dad's dangerous activities as the Arrow, but Felicity took the time to explain to him why his dad was a hero. She let William watch footage of Oliver fighting criminals while she talked to him about how she was able to love and trust Oliver while also worrying about him. Even though Oliver wasn't physically there for the conversation, it was an important bonding moment for the three of them and William got to see finally his dad as a hero.
Thea Finding Out Oliver Was The Arrow
Oliver did not reveal to Thea that he was the Arrow until the middle of season 3, making her one of the last main characters to know. Oliver admitted that he had been lying for a very long time. He tried to explain he kept the truth from her for her protection, but he expected Thea to be furious. Instead, to Oliver's surprise, Thea thanked him. For years, she had thought he was just a selfish, flaky big brother and a bad liar. It was a beautiful brother-sister moment when she realized he had been the hero looking out for her and their city all those years.
Oliver and Felicity Raising Mia
Oliver and Felicity semi-retired at the end of season 7 to take care of their family, especially their new baby, Mia. Oliver missed the beginning of his son's life, but he got to be there for Mia's birth. He only got to spend a brief amount of time with his wife and daughter before being taken away by the Monitor, but the montage of their family is a heartwarming display of Oliver's growth as a character and as a father.
Oliver Talking To His Adult Son
Thanks to time travel, Oliver had the chance to meet his children as adults and have a meaningful conversation with William. He got to know how well his son turned out and express that he was proud of him.
There was also another touching moment between the father and son when William told Oliver that he was gay, to which Oliver lovingly expressed that he and Felicity already knew and accepted him for he was.
Oliver also added that he was upset that he never had the chance to talk about important things with his children, but William comforted him by saying that he, Oliver, and Mia could "have the chance to get to know each other now."
Oliver and Felicity's Wedding Reception
Oliver and Felicity eloped spontaneously with a very limited group of people, but they later had a reception for the rest of their friends and family. The episode was full of many memorable moments, not the least of which being when Quentin Lance gifted Oliver with the watch that his father gave him on his wedding day.
Both of Oliver's parents were deceased, so Quentin knew he was essentially the only father figure present for Oliver at his wedding. Without saying it, both of them acknowledged that Oliver was like a son to him. In many ways, as Oliver tells Lance at the end of season 6, Quentin was a better example of a father to Oliver than Robert Queen had ever been.