It's pretty rare to see a fanfic centered around Oldeus, but it's always nice to see. The story is pretty good; the only major issue with the story, in my opinion, is Rudy's character. In the Oldeus timeline, Rudeus suffers horrific trauma after horrific trauma and becomes a depressed, homicidal, womanizing alcoholic (albeit a very powerful alcoholic) that's hellbent on revenge and becoming stronger. So, you'd expect after he time travels these things would deeply affect him, but said events feel to have little impact on his character. That being said, the story isn't finished, and the author may very well be planning to address this concern. On a more positive note, in almost everything else I can think of, the author does very well, especially in his writing of Paul and Rudy's interactions. Sometimes it honestly feels like how Rifujin would write the two.