Chloe O’Bell: One of the children that was entrusted by Shizu to Rimuru and later became one of Rimuru's first students. Initially, just like the rest of the children, Chloe was wary of him. However, as Rimuru made efforts to become closer to them and teach them properly, all of them became close and respect Rimuru greatly, calling him "Sensei". Among those children, Chloe becomes the one with the most affection towards Rimuru as she falls in love with him, even declaring she loves him though Rimuru didn't take that seriously initially. Even after being controlled by Yuuki, she still thinks of her Sensei and regards him highly, to the point that she said that Rimuru is the key to change the future. Chloe is also an important person to Rimuru as he decides to definitely save her from Yuuki. It's interesting to note that, whether intentionally or not, Chloe and Rimuru are somewhat stuck in a stable time loop, as his bringing her to Ramiris granted her her powers over time and saved her life, while her tinkering in the past led to Veldora being sealed exactly where Rimuru would be born centuries later, in other words, the two of them are directly responsible for each other's existence and rise to power.
Sakaguchi Hinata: Their relationship has a rocky start since they both were initially hostile to each other, though it's mostly due to Yuuki's manipulation in the background. However, as Rimuru intends in keeping Shizue's promise, he always tried to reach an understanding with Hinata, to the point of going easy on her after he became a Demon Lord and sparing her Holy Knights during their subjugation of Tempest. For Hinata, she looked down on Rimuru at first as she regarded him as just another "monster", but after learning he survived and evolved into a True Demon Lord, she raised her views of him and became more cautious towards him. In the end, however, after being convinced by Shizue's spirit and reaching an understanding with Rimuru, Hinata becomes one of Rimuru's most trusted allies and they even address each other casually. It's important to note tht both Hinata and Rimuru, before the latter ascended as a Demon Lord, had their thoughts restricted by Yuuki, thus making it impossible for them to think of compromising, especially in Hinata's case, as her restriction was so complete she was more or less mechanical minded. Hinata has grown to respect Rimuru highly as she totally agrees with Tempest becoming the "center" of the world, she also understands Chloe's faith in him and seems to share it. Amusingly, when Rimuru was being mocked and Hinata was being insulted by a group of officials at the assembly who believed the former could be turned into a minion while the latter only achieved her position by sleeping with a cardinal, they seemed able to communicate with their eyes, both when they were wondering what the other would do and when they calmed down because Shuna retaliated on their behalf before either of them could do so.
Veldora: Rimuru and Veldora became fast friends after meeting each other and are now best friends to each other. Veldora has such a great amount of trust in Rimuru that he allowed Rimuru to devour him the first time in order to be freed from his sealed prison. When Veldora was captured by the Eastern Empire, Rimuru felt a great anger that he never felt before, indicating their closeness to each other as if they're families. Since they named each other, Rimuru and Veldora can be considered son and father or brothers to each other.