Griez was a former Marleyan soldier who served on Marley's Navy and was part of a survey fleet sent to Paradis Island after the failed Paradis Island Operation. After being taken captive on the island, he began working as a waiter in a restaurant inside the Walls.
Griez was a young man with dark hair, which was kept closely shaved. He had originally only been seen wearing waiter's clothes. After he was freed from the restaurant by members of the Yeagerists, he wore a dark jacket and pants like the other Anti-Marleyan Volunteers.
Greiz was characterized, just like many of his countrymen, by his severe anti-Eldian sentiment. Despite having been captured and forced to live on the island, which could have made him see that the Eldians living where just human beings like everybody else in the world, something that has been the case with multiple captured Marleyans on the island, he still continued to hold on to his ingrained fanatical hatred towards Subjects of Ymir.
Appearance: Griez was a young man with dark hair, which was kept closely shaved. He had originally only been seen wearing waiter's clothes.
Personality: Greiz was characterized, just like many of his countrymen, by his severe anti-Eldian sentiment. Despite having been captured and forced to live on the island, which could have made him see that the Eldians living where just human beings like everybody else in the world, something that has been the case with multiple captured Marleyans on the island, he still continued to hold on to his ingrained fanatical hatred towards Subjects of Ymir.
Griez in the story: Griez is among the Marleyan soldiers who are dispatched as part of a fleet to survey Paradis Island, and is summarily captured by the Eldians living on the island. He is put to work as a waiter in a restaurant run by his fellow soldier Niccolo. While waiting on a group of Military Police Brigade officials, Griez is ordered to bring them more wine, and goes to retrieve a specific bottle from Niccolo.
Source: Attack on Titan Wiki, available under CC BY-SA 3.0.