Ness was a man of average height and build. He had a welcoming face with a thin mustache and a stubble around his jawline. He was notable for the white bandanna that he wore around his head, which concealed his bald spot, but showed light brown hair along the sides and back. He was never seen without the standard Scout Regiment uniform, but he donned the green cloak during expeditions.
Ness was a serious leader who never took his job lightly. At the same time, he truly cared for the new recruits and wanted to make their first expedition as easy as possible for them. This was proved as he was the one who taught them about the Long-Distance Enemy Detection devised by Erwin Smith. Ness was not a fan of fighting Titans and always tried to stick to the idea of avoiding them outside the Walls, however, he never hesitated to fight them when it was necessary.
He also had a more lighthearted side, as was shown when he thanked his horse for coming back to him.
The following day, Ness introduces himself to the new recruits that have joined the Scout Regiment. As he is introducing himself his horse, Charrete, begins trying to chew on his hair. Ness is placed in charge of teaching the recruits Erwin's long range enemy scouting formation, and ensuring that they memorize it.
During the 57th Exterior Scouting Mission Ness encounters an abnormal Titan in a field, and uses his omni-directional mobility gear to sever the Titan's ankles, causing it to fall over and allowing his squad mate Luke Cis to destroy the nape of its neck. To his joy, Ness' horse returns for him, and he and Cis resume the expedition.
Almost immediately after, they encounter the Female Titan. Caught off-guard by its speed, Ness is nearly crushed underfoot before noticing that it is heading for Armin Arlelt. He and Cis attack the Titan's nape, but it easily intercepts and crushes Cis, before catching Ness' line and whipping it to the ground, killing him instantly.
During the Battle of Shiganshina, as Erwin Smith begins to lament the dwindling hopes of his dream, Ness stands among the many fallen Scout Regiment comrades in Erwin's mind, wanting to know if their deaths had meaning.