Dennis Macfield/Relationship

Yūri
Yūri appears to be one of Dennis' acquaintances and both seems on good terms with each other. Yūri seems to trust Dennis to help with his mission on locating Yuzu and her Dimensional counterparts, while Dennis' trust in Yūri is shown when he left him alone to capture Yuzu and her dimensional counterparts, confident that Yūri alone is enough to complete the task.

Yūya Sakaki
Dennis stated that he greatly admired Yūya's father and also admired Yūya as fellow Entertainment Duelist. His admiration towards Yūya is what prompted him to save Yūya from Ken and Makoto. Yūya also quickly got impressed by Dennis' Duel that reminded him of his father. Their mutual interest in Entertainment Dueling made them quickly becoming friends and both promised to once again Dueling together again. Thus, Yūya felt betrayed once knowing Dennis' true identity. It was still unclear whether Dennis' admiration for Yūya and his father is real or just a facade like Sora did.

Shun Kurosaki
Dennis quickly has an antagonistic relationship with Shun even before he revealed his real identity, which was started from when both of them mocked their respective Xyz Monsters. Shun immediately got suspicious of Dennis' identity and since then determined to expose him, much to Dennis' annoyance. Once confirming Dennis' identity as an Academia Duelist and furthered by the revelation that Dennis was partly responsible for his sister's kidnapping, Shun developed intense hatred for Dennis, brutally defeating him in their rematch, trying to turn him into a card, and even lashed out his anger by attempting to punch him. Unlike Sora, despite his devotion to the Academia and badly injured by Shun, Dennis doesn't show any grudge towards Shun.

During a conversation with Yūshō, Dennis revealed he felt he couldn't rejoin the lancers due to having betrayed both Yūya and Shun, implying a certain amount of guilt and regret for his actions to the the former.