Adelbert Steiner (often referred to as "Steiner" or "Rusty") is the Captain of The Knights of Pluto, a group of misfit dope soldiers of the kingdom of Alexandria. While he is in charge of such a motley crew, he does have high ranking, only behind the royal family, Beatrix, and Zorn and Thorn.

Throughout his adventures with Zidane, he grows from strongly disliking him to have a great respect for him. He holds a deep friendship with Vivi and trusts his judgement, which makes them a powerful duo in battle. As a constant through the travels of the party, he remains steadfastly loyal to Princess Garnet. He has a great moral dilemma when he is no longer sure if he can continue to follow the orders of the Queen. He at first hinders but ends up helping the Princess throughout their journey, as his primary duty is to protect her at all costs. Ultimately he falls in love with Beatrix and they form a relationship, as is shown in the final cutscene of the game where, together, they hold of Beatrix's Save the Queen sword up high, as a sign of their love, and the unity and peace in all of Gaia.

Physical
Steiner's physical appearance is characterized mostly by his armor. As is seen (and mentioned numerous times) in Final Fantasy IX, he wears shabby armor, poorly put together and kept in less-than-perfect condition (hence Zidane's nickname for Steiner, "Rusty"). The armor is bulky too, giving Steiner the appearance of being large, and possibly out of shape. He can often be heard from a distance from the clanking of his armor's plates. He carries an enormous sword with him and can usually be seen with a scowl on his face.

Aside from his apparel, Steiner is also a large man, taller and more well-built than most of his allies (though he appears to have 'chicken legs').

Attitude
Steiner also has a more stubborn view on things. Early in the game, he is a mindless, obedient servant to the Queen and Princess Garnet, never thinking for himself. He's very uptight and snobbish, mocking the lower-class and considering those who do not directly serve the royal family as low-lives. He treats many around him with little respect, save his superiors, and the ever-charming Vivi. As the game progresses, however, he learns to be more caring and understanding, and eventually begins to think for himself, including "betraying" Queen Brahne when he learned of her mistreatment of Garnet. With the world he thought he knew being a lie, it made him change how he felt and thought of many things. He even befriends Zidane! And, in the end, he even opened up his heart and found love in the form of his former rival, Beatrix.

Abilities
Steiner is able to use several different abilities in the game, including his very useful "Sword Arts" skills. These abilities are:

• Darkside - Sacrifices 12.5% of max HP to deliver an attack 40% stronger to one enemy.
• Minus Strike - Attack one enemy, dealing damage equal to difference between Steiner's current and max HP.
• Iai Strike - Causes instant death to an enemy with a 30% accuracy.
• Power Break - Reduces enemy's strength by 25%, with a 50% accuracy.
• Armor Break - Halves enemy's physical Defense, with a 50% accuracy.
• Mental Break - Halves enemy's Magic Defense, with a 50% accuracy.
• Magic Break - Reduces enemy's Magic Power by 25%, with a 50% accuracy.
• Charge! - Causes all allies in HP Critical status to attack an enemy.
• Thunder Slash - Deals Lightning-elemental damage equal to 19% of its Max HP. Almost always misses due to a glitch.
• Stock Break - Attack all enemies, doing 1.5 times normal damage.
• Climhazzard - Attack all enemies, doing non-elemental magic damage at twice normal damage.
• Shock - Attack one enemy, doing three times normal damage.

In addition to his Sword Arts, when Steiner is in the party with Vivi, he can use the Sword Magic abilities. Any attack spell in Vivi's arsenal is combined to Steiner's sword, causing an attack infused with the magic. The MP is only drained from Steiner, leaving Vivi's MP untouched.

It should also be noted that the Doomsday Sword attack will not harm any allies, unlike Vivi's spell of the same name.

Equipment
Steiner uses Broadswords as his primary weapons. Some bear famous, recognizable names from previous Final Fantasy games, such as the Ragnarok and Excalibur. He is the only character who can get a weapon with an attack power higher than 100. It's called Excalibur II, and can only be obtained by reaching a certain point late in the game in less than 12 hours. This was made easier by the PS1/2's ability to skip FMVs by opening and closing the PS1/2 lid/tray when an FMV starts. In-depth guides have been written solely for obtaining Excalibur II, down to the every allowable random encounter, which items to pick up, who to give what equipment, which Blue Magic Quina should learn and so on. Even so, it is still very normal to reset the game multiple times due to an unwanted random encounters or a boss taking too long to defeat or other factors.