Duke Freed is the kindest, cleanest, and most humble character you are ever going to meet, particularly out of all of the super robot pilots.  He never hurts anybody, he doesn't foolishly chase women, and he is never selfish.

Duke Freed hates war, fighting, and destruction.  He does not feel in any way proud of his machine and does not boast about his abilities like other characters such as Koji with Mazinger Z, or particularly Tetsuya with Great Mazinger.

In the first episode of Grendizer, Duke was shouting out loud in anger, as he stared at the red moon, that he does not want to pilot that "thing" again, as in Grendizer.  The Grendizer super robot had been buried under the Space Science Centre shortly after crash-landing on Earth, and Duke Freed hoped that he would never have to see it again.

Duke Freed came to Earth to live a peaceful life, but when he realized that the Vegans' next target is Earth, he became very worried about the huge responsibility that was before him.  He did not want this responsibility and his fear was that he might have to relive the nightmare on planet Freed.  In the back of his mind, he knew that he had to fight the Vegans and protect the Earth and its greenery that he loves.

As Duke Freed accepted the situation his conscience developed a strong will to always fight the enemy no matter what the costs may be, even if it is his own life.  Even if Duke knew that the enemy was mightier, his bravery and dedication to Earth drove him to fight.

Duke also wanted to avenge what had happened to his planet and parents.  What made the situation more complicated was the legendary Koji Kabuto who was not an ordinary person to deal with.  Koji came to the Space Science Centre to research the UFO sightings that have been happening.  Koji found Duke to be strange when he first saw him and they became friends and brothers after a bitter rivalry, and Koji found out Daisuke is Duke Freed.

Duke Freed always watched Koji very closely.  Duke learned that the former Mazinger Z pilot is an experienced fighter, but also one that takes a lot of risks.  Duke knew that the Vegans are not an army to mess with, and he looked over and protected Koji as his younger brother.

Duke Freed loves nature and is very kind to animals as one observes in the Grendizer series.  He also gives special attention to children and tries to keep them happy as much as possible.  Duke really enjoys working on Shirakaba farm for Danbi Makiba, and he will sit on quiet nights and play his planet Freed's theme on his guitar.  Duke is generally a very quiet person with a plain look on his face.