Tragic backstories are great for characters to have. It gives them something to overcome, helps build a connection with the audience as they cheer them on and allows characters to be viewed at what is usually the lowest point in their lives. They are great tools for building empathy, which is necessary for an audience to want to see a character succeed.
The Straw Hat Pirates all have some level of tragedy in their lives, long before they ever met the rest of the crew. Whether it's the death of Nami's adoptive mother, Sanji's abusive family or in this case, Robin's homeland being destroyed, the fans love and respect what these characters have been through. A pivotal character in Robin's backstory, however, seems to have a different fate than what was originally presented.
Jaguar D. Saul Was Once a Powerful Marine
At the rank of Vice Admiral, Jaguar D. Saul was quite high in the Marine hierarchy, but he never let this go to his head. Despite having a lot invested in the Marines, Saul refused to follow an order to destroy the island of Ohara. The Oharans were the foremost archeologists in the world of One Piece and were found to be studying the Void Century -- an act strictly forbidden by the World Government.
As punishment, the island was destroyed via a Buster Call, which saw several warships sent to the place in question to be erased from the world. Refusing to carry out the order, Saul left the Marines, only to coincidentally wash up on Ohara anyway, where he met Nico Robin, future archeologist of the Straw Hats.
Saul Squared Off Against Aokiji to Protect Robin
Aokiji was also sent with the Buster Call to destroy Ohara and battled against Saul, who was attempting to destroy the invading warships. Seeing his valor and courage to protect Robin, Aokiji let Robin go free, making her the only survivor of the Ohara Incident, but the most recent chapter proves that this isn't the case after all. After decades of thinking that Saul died on Ohara, a fan theory had recently circulated, speculating that Saul was indeed alive after all. Aokiji defeated Saul using a technique called "Ice Time Capsule," which saw the giant entirely encased in ice. As the name of the technique implies, Saul was not defeated but rather frozen in place to be thawed at a later point in time.
Chapter 1066 saw Dr. Vegapunk describe how the knowledge of the Oharans was spared from destruction by a group of giants, led by a man covered head to toe in bandages, who Robin correctly guessed was Saul. It's likely that Saul was spared by Aokiji out of mercy, as the Ohara Incident completely changed the way the future Admiral perceived the idea of justice -- and with his recent return to the story, fans might get an answer sooner rather than later.