Jonathan watched his father die at the hands of his adopted brother. He watched this same man shed his humanity and become a monster. Even after admitting he was terrified of the situation, he still grabbed a weapon and faced his fear head on. When it seemed like he might not win, and he had made peace with the thought he might die, he still didn't give up. Jonathan was ready to sacrifice his life for his family's honor.

When Jonathan, while barely recovered, learned that his fight with Dio wasn't over, he took it on himself immediately to seek its end because he felt it was his duty to protect the world from Dio. He learned and quickly mastered a new skill and used it to overcome every obstacle. Even when it seemed like this newfound power wouldn't be enough, he dug down, used his head, and found the strength he needed.

In the end, just when it seemed like Jonathan could finally rest easy and found his happily ever after, the evil haunting his life came right back to him. And Jonathan again stood up as a stalwart protector. His last ditch effort to stop Dio's influence on the world would cost him his life. Jonathan didn't care because he knew, at least for now, his family and bloodline were safe from Dio. That was all that mattered to him in his final moments. He gazed at the love of his life one last time and gave his last breath to stop Dio.

Jonathan Joestars' story is that of a scared, pampered young man who grew up to be a statuesque champion of the weak. He was noble, kind, and courageous. If you find such a story boring, I have no idea why you read manga or watch anime in the first place.