I’m more used to the Japanese names, so I will put down the US names next to it just in case. Plus some of the background story was removed from the dub.
What happens when somebody not used to lose starts failing?
They break, of course
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To lose is an important part of growing up. Whenever we fail, we learn how to adapt and to react to that: some people give up and try something else, others insist on that, some change strategies or use it on their favor and so on.
But Ryo (Zane) was always the pinnacle of perfection. The best Cyber-Style disciple and graduated from Duel Academy without peers (his best friends Fubuki (Atticus) and Fujiwara couldn’t make it at the time). He had everything by the end of school year: he was the honor student, the Kaiser of all. Nobody could reach him. During his graduation duel against Judai (Jaden he said):
” But, at the same time, that’s also my limit.
In a way, being “perfect” means that you won’t chase after your limits.”
Being perfect, means that he couldn’t improve anymore. He was the best he could ever be.
When he got out from school into the real world, he found out he wasn’t nearly good enough. All the respect he had to the other opponents, all this idealized vision he had meant nothing. He has nothing to offer.
Not being used to lose meant he didn’t knew how to adapt to the new situation
Ryo was hurt and broken and because of that he suffered a total breakdown. If all his values were useless, he just needed new ones. So when somebody offered him a chance, any chance to regain his glory he reached it out without even thinking.
It was done to show how hard it is to be a young adult, to get out from the school thinking that you will keep on your status quo once you get into the real world. It’s not like that: you must conquer your place in society. And you will fail, but you can’t give up no matter what happens. Ryo thought he couldn’t change, but he did becoming something his past self would hate. Many people actually grow up to be like that, it is a sad reality.
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By the end of Season 3 we found all that everything he did in season 2 had consequences: his heart was failing. Even so he went to the other world after Judai and his friends, and gave his brother a peep talk when it was needed, showing that even being a jerk he did cares about Sho (Syrus). That had a profound effect on the younger sibling and gave him strength. As for Ryo, he was just looking for a strong duelist to face and die in battle and not as an useless bedridden sick guy. His pride wouldn’t allow that.
And in season 4 his body is so weak he can’t even move around out the wheelchair for long. It is obvious that was made to show how the mighty can fall and destroy themselves in the process. Ryo was made an example that adult life can be hard and if you make the bad decisions like he did you may destroy all your future.
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This was also done to show Sho’s growth. From the wimpy guy who always relied on somebody (Judai or Ryo) he became one of the three best seniors in his year. A major plot point was when Ryo passed down his deck on to Sho and he improved the deck with his own strategies becoming even stronger. You shouldn’t live in anybody’s shadow or think that you can’t get any better. It is part of growing up: you will change, you will get better. Or you can get worse. The path you chose is entirely up to you.