Luke Notos Greyrat

Luke was born into the Notos Greyrat family as an Asura Kingdom high noble. He was tasked at a very young age of being the Guardian Knight to second princess Ariel Anemoi Asura alongside Derrick Redbat. He is very fervent in his duties as a guardian despite his frivolous attitude toward girls and his mediocre skills.

[Spoiler] Luke is indirectly responsible for curing Rudeus' erectile dysfunction by giving one of his aphrodisiacs to Sylphiette. [/Spoiler]

[Spoiler] He was Hitogami's apostle in stopping Rudeus from supposedly using Ariel for his own personal gains. However, he was able to resist Hitogami's words in the end. [/Spoiler]

[Spoiler] In the original timeline where Rudeus does not exist, he marries Eris and they become a happy couple together. [/Spoiler]

(Source: Mushoku Tensei Wiki)