Julius Juukulius/Relationships

Joshua Juukulius
Joshua and Julius share a very close relationship, befitting that of two brothers, though it should be noted that the two haven't been confirmed to share a blood relation, and likely call each other brothers due to knowing each other since very early ages and growing up together. The two grew up together in the Juukulius manor and, due to Joshua's condition, he spent much of his childhood bedridden and observing his older brother practicing with the sword. Julius loves Joshua dearly, and often spent hours and hours in his room, reading him stories and conversing with him about different topics.

When they were both small children, Julius snuck Joshua out of the mansion and the two went on a long ride with Julius' Earth Dragon. Later, Joshua developed a severe cough which almost killed him. To this day, Julius blames himself for that little incident.

Reinhard van Astrea
Seeing Reinhard for the first time was a big turning point in 10 years old Julius' life, making him realise his lack of capabilities in comparison to Reinhard. That caused him to rethinks his behavior, turning from an arrogant noble child into the knight he is today. Despite that, they only became properly acquainted after Julius was enlisted in the Royal Guard at the age of 16. Julius considers Reinhard to be one of his best friends and trusts him with his life. Although sometimes the two come to disagreements, Reinhard continues to respect Julius' decisions. During Reinhard's duel with the Empire's Blue Lightning–Cecilus Segmunt, it was hinted that Julius developed a great deal of jealousy towards Reinhard, however, the reasons for such feelings aren't entirely clear.

Following his duel with Reid Astrea, Julius finally swore to crossing swords with Reinhard in a sparring match.

Reid Astrea
During the events of Arc 6, Julius was forced to duel the legendary First Generation's Sword Saint Reid Astrea. From the very beginning, their ideals heavily clashed with each others', as Julius–the Finest of Knights–could not believe or accept the crude and vulgar ways of the Sword Saint Reid Astrea–the pinnacle of the sword. Despite their heavy disagreements, however, Julius displayed unbound respect for Reid, even though it pissed the Sword Saint off to an alarming extent. Due to Julius' chivalry and honoured way of life, Reid did not hesitate to give the Knight a beating as often as he could. Finally, during their last duel, Julius managed to push Reid to his limit, landing a would-be devastating blow to the Sword Saint's face and blowing off his eyepatch. Following that exchange, Reid was finally willing to accept Julius a knight, remembering his full name, grasping an actual sword (rather than the pair of chopsticks he wielded up to that point), going beyond the rules of the trial, as Julius has already passed it when successfully landing a blow. After a stroke of luck, Julius managed to pierce Reid's chest, landing a devastating and final blow of the duel–due to Reid's incompatibility with Gluttony's body, his soul (which Gluttony ate, prior to the duel) shattered, marking the end of the First Generation's Sword Saint. However, right before departing from the world for the final time, Reid delivered a bit of praise towards Julius, and Julius admitted that it was Reid's win from the very start.

Felix Argyle
He was commissioned to watch over him when he joined the Royal Guard, they got along quite well and had a friendly relationship.

Anastasia Hoshin
Julius has absolute loyalty towards Anastasia. They both trust each other knowing the other would do their job correctly. He later learns that his liege was possessed by Echidna. After the battle with Reid Astrea, both of them started their relationship once again.

Ricardo Welkin
Despite being a higher class, he views Ricardo as a trustworthy ally and a comrade. When Julius began to doubt himself during the events of Arc 5, Ricardo lifted his spirits and remove any doubt he had. Ricardo sacrificed his arm in order to defend Julius from Roy, but his name was eaten and he was defeated regardless.

Natsuki Subaru
Julius and Subaru's relationship started out on the wrong foot; mostly because Julius's noble mannerisms caused him to come over as haughty from Subaru's 21st-century perspective. Still, it didn't turn truly antagonistic until Subaru offended the whole Royal Knight garrison, prompting him to publicly humiliate him in a mock duel. However, in a way, Julius was actually protecting Subaru here, as most of the Royal Guard outright called for his execution before this.

Despite their bad start, their relationship got better following the battle with the Hakugei, after they both apologized and Julius even admitted he may have acted rashly. The two then proceeded to work together to defeat Petelgeuse. However, both still voiced their dislike for each other afterward.

After having his name eaten, Subaru is now the only one who can remember Julius. During their trip to the Pleiades Watchtower, in search of a way to restore Gluttony's victims, their relationship has gotten somewhat better, and eventually, they both became close friends with mutual respect for each other.

Roy Alphard
Julius had an ominous feeling that creeped him out when Roy kept calling him "brother". Roy is the one who ate Julius's name, erasing the memories of him from everyone he met, and ate Joshua's name and memory, thus erasing his existence from the world.

Emilia
Although their first meetings are not shown but despite being of the opposite factions, Julius holds great respect for Emilia and also admires her. In volume 4 epilogue, he says that Emilia's nature is too unprofitable, but he doesn't want that to change because that is what makes her way of living noble and beautiful as she is.