Yūri/Relationship

Leo Akaba
Yūri appears to be very loyal to Leo, obeying all of his commands. This loyalty seems to be originally came from the fact when he was a child that unlike the others who feared Yūri, Leo acknowledged and accepted his skill and allowed him to do Duels that he likes and turn his opponents into card once the inter dimensional war begin, something that made Yūri happy. Yūri will do his best to fulfill Leo's given order and didn't dare to disobey it. As such, despite wanting to turn Yuzu into card, he didn't do so because Leo had ordered him to bring her back unscathed. Despite his origin, Yūri seems to be one of Leo's most trusted Duelists amongst Academia, as he personally gave only Yūri alone the order to capture Yuzu and her dimensional counterparts, something that only a few Academia Duelists knows. And Leo only ordered Yūri to fulfill the mission, proving that Leo is confident in Yūri's skill.

Despite Leo knowing the origin of Yūri, Leo seems to not care if he might awaken the demon again. The consequence is Leo's teaching caused Yūri's mind to become so warped from carding many people under his order to the point he no longer care about Leo and his goal, only wanting to card people for his own enjoyment. From then on, Leo sees Yūri as nothing but Zarc's reincarnation that will destroy the world and determines to put a stop at him and his counterparts at any cost.

Yūgo
Yūri first met Yūgo when he kidnapped Rin, Yūgo's childhood friend. Since then, Yūgo bears a strong hatred towards Yūri and traveled from one dimension to another to hunt him down. Yūgo's obsession on Dueling him quite annoyed Yūri, who only saw Yūgo as bothersome and didn't worth his time, usually ignoring Yūgo when the latter challenged him to Duel and instead continuing his mission. Yūri's interest in Yūgo started to spark when he found out that Yūgo had defeated Serena, and finally agreed to his challenge as he now considers Yūgo capable of providing more fun to his hunting game. After he won his Duel against Yūgo, Yūri came to respect Yūgo as a Duelist as he expressed how much fun he has when dueling the former, regretting that he didn't do it sooner and even apologized for treating him as a nuisance until now. After Zarc's defeat, the hostilities between them seemed to have ceased to be, and their relationship has improved significantly, particularly Yūgo not showing any kind of hostility against Yūri and the two, together with Yūto, even willingly work together to support Yūya.

Yūya Sakaki
Yūri and Yūya initially didn't interact much until much later in the series. Yūri came to got interested in Yūya after coming into realization that he and Yūya were originally a same person and quickly developed a strong obsession to merge with Yūya. His desire makes him possessive of Yūya, exclaiming that Yūya belongs to him and he won't hand him over to anyone. Yūri will do whatever it takes to merge with Yūya, going as far as tormenting Yūshō in front of Yūya to make him lose control of himself and continuously tempts him by tormenting while attacking Yūya in their Duel. Yūya developed quick hatred for Yūri the moment he carded his father right in front of him, which enough to make Yūya succumbed to Zarc's power with only thought of defeating Yūri. After Yūri lost to Yūya, the former gained a degree of respect for him, happy at the fact that Yūya is the first person to defeat him since they are, essentially, the same person, and he is content with being absorbed by Yūya.

After Zarc's defeat, Yūri seems to have had a change of heart, giving Yūya his encouragement together with Yūto and Yūgo when Yūya was afraid to summon their dragons. And Yūya, in return, no longer show any hostility towards Yūri and even answered Yūri's expectation by summoning "Starve Venom Fusion Dragon", not wanting to disappoint him, which seems to indicate that Yūya may have forgiven Yūri. Their improved relationship is proven when Yūya asked for his counterparts' support, including Yūri who continuously assisting him throughout his Duel against Reiji until the end willingly and is happy for him when Yūya won.

Yūri's soul also caused Yūya to adopt Yūri's habit of touching his hand when declaring "Fusion Summon", a trait Yūya has never shown before.