True it doesn't really matter to me whether it is based on anime; it's more about the plot of how two people were close at a young age were separated and now had to confront each other (or something along those lines). The reason I mentioned those three anime is because that is where I got the idea from and they are what sparked my interest in such storylines (Lelouch vs. Suzaku, Kira vs. Athren, Ryner(roland) vs. Kiefer(Gastark).)