Hokori was initially reckless and quick to anger when he felt that he or those close to him were being treated unjustly, although he preferred to use trickery to get what he wanted as opposed to violence. He kept an open mind though, not afraid to envision things being different and going against the advice of others in pursuit of doing what he felt was right or necessary. Despite being the disappointment of his parents, he was determined to live a happy life regardless of his parents contempt.
Once the whole marriage fiasco and disownment problems hit, Hikori's personality significantly changed. He became sarcastic and darkly humourous, all with a laid back attitude that made it seem like he stopped caring about the world. Also he became more calm and collected, losing the recklessness of his younger years save for the occasional angry outburst. Since devoting his time to the study of history, he's become passionate about the subject. Of special focus to Hikori is the various terrorists Avatar Korra had to fight during her time, with whom he has sympathized with immensely.
Hokori was born to Olmak and Karra Arjalinerk, two wealthy pro-benders who retired, settled down, and became even wealthier when they founded Astounding Arjie's Electric Company and eventually created a monopoly on the business, mainly in the Earth Kingdom. Between Olmak's powerful lightning generation and Karra's skilled waterbending leading to their hydroelectric business, the two were proudly expecting a child who would be even more skilled then themselves. So when they found out Hokori was a non-bender when he was around 4, to say they were disappointed was an extreme understatement. Though they trained him in fighting and weaponry, primarily a spear as it was the cheapest weapon they could buy, Hokori could never get his parents to respect him or to care for him. He was watched primarily by nannies, mostly cranky, rude old women, before his parents sent him to a trade school for learning how to properly manage a company. He might've been a huge disappoint to his parents, but he was the only heir to their company and they didn't want him to run it into the ground. Hokori protested, as he wasn't interested in running a gigantic company but rather learning history and eventually teaching it (his dream was to teach history at the illustrious Ba Sing Se University), but his parents only laughed and mocked his dream while sending him to trading school. When the trading school closed down due to corruption charges (many of the richer parents were paying off the school so their children would pass with perfect marks), Hokori tried to run away so that he wouldn't have to go back home. He donned a mask and disguise and fashioned himself as Atarashi the spear dancer. He joined a circus that was on its way to Ba Sing Se, but a week into the trip one of the performers found out who he really was. Due to jealousy, the performer had Hokori taken by the police and brought back home. His parents gave him hell, and for running away Hokori was secluded from the outside world and never to leave the home again.
Two weeks later Olmak and Karra divorced after Karra found out that Olmak had been with another woman named Lu Tien and had been raising another son behind her back. Devastated, she left him and engaged in a horrible legal battle for rights to the company. The legal battle raged for two whole months before Karra was killed in an "unrelated" home invasion. Thus Olmak's new wife and son Gopan moved into the house. While Lu Tien treated Hokori as horribly as Karra did, if not worse for not being her son, Gopan was an entirely different story. Gopan was a compassionate fellow, though a bit naive, and loved his half-brother like they had been brothers since birth. Olmak loved Gopan as he was a powerful Earthbender, and easily learning Metalbending, but Gopan didn't return the appreciation beside polite thanks. Hokori wasn't sure how to respond to Gopan's kindness, considering his former family life, but slowly and surely warmed up to Gopan. Eventually Gopan convinced Olmak to let Hokori go outside again on the condition he stayed with Gopan, and by Gopan's side he started making friends. That's where he met Tang Shen, and though both were shy with Gopan's urging they started to date. In time infatuation led to love, and on their three year anniversary Hokori proposed, to an astounding yes.
When Olmak got wind of this, he became more infuriated then he ever had before. No son of his was gonna marry some poor peasant girl. He demanded that Hokori break off the relationship, and when Hokori refused he tried to force Tang Shen to call off the engagement. Thankfully Gopan protected Tang Shen's family financially, and Olmak was unable to either bribe or blackmail the family into doing anything. Furious at Gopan's involvement preventing him from stopping the wedding, he confronted his son the morning before at Tag Shen's house. When both Tang Shen and Hokori adamantly refused to call off the wedding, and adding insult to injury was the fact Tang Shen's father was to be the replacement for Olmak at the ceremony, Olmak snapped and attacked. In the resulting fight Tang Shen was killed by Olmak's lightning, and Hokori slashed and ripped and cut and beat his father so badly that by the time police came Olmak was barely recognizable. On his deathbed, Olmak renounced Hokori as his son and heir and instead chose Gopan as his only son and sole inheritor of Astounding Arjie's. After Olmak's death and funeral, which Hokori refused to attend, Gopan offered to split the company fifty-fifty with Hokori and fund a college education for Hokori so that he could become a teacher. However, disillusioned by Tang Shen's death Hokori refused and instead fled to the mountains where he donned his old mask and became the bandit Yami, raiding trucks and stealing money from the rich. For a year this went on before Gopan himself finally went into the mountains and defeated Yami, knowing it was really Hokori. Clearing Hokori's name with his powerful lawyers, Gopan made his offer again to Hokori. Hikori couldn't accept though, and instead opted to go to Republic City where he could live a new life without the constant reminders of Tang Shen. Agreeing to the plan, Gopan stated that Hokori always had a place in his home and a good job in any Astounding Arjie's factory if he needed it, and that Hokori was also legally able to claim his birthright if he so chose. Thankful for his brother's kindness, he left the next morning on a boat heading to Republic City to start his new life.