Theory why Darius is Vladimir's rival

I'll state right now that I will ignore the IOW retcon for this thread. I have thought about the rivalries in the game and here's my theories about why would Darius have a rivalry with Vladimir.

Darius hates Vladimir probably because of three reasons: the hemomancer is a pompous aristocrat, a draft dodger and a criminal. In Vladimir's judgement, he mentioned that he wanted to bring "honor to his noble house," which could mean that Vlad had an aristocratic background before he left Noxus in his youth. He also said that he spilled blood from his first victims on his "fine clothes" which supports this idea.

I have observed that military service is compulsory in Noxus for at least six years and its citizens are expected to be ready to be drafted asap. When Vladimir killed for the first time, he was fifteen years old. Unless Vladimir already went into military service for six years, he avoided being drafted into the Noxian military, in addition to avoiding punishment for committing two homicides.

With this evidence in mind, Darius would be Vladimir's antithesis. Darius is from a humble background; he's a self made man and a patriotic soldier. It's explicit that Darius envisions his city-state being purged of its weaknesses through personally killing the corrupt and opulent nobility, which Vladimir is a part of.

So what you think? Do you guys want to share your theories about unexplained rivalries?