Ulrich Stern shares a room with Odd on the Kadic campus. Being an introvert, Stern doesn’t say much ‘bout his personal life; he is evasive when someone asks of his family&has a bit of trouble opening up to people. He tends to hide his feelings in order to let 'em explode in battle. On the outside, Stern appears emotionally strong, dealing with hidden issues few could understand (one being his parents, who are hard to please&have high expectations). On Lyoko, his samurai get-up includes katanas that allow him to slice enemies apart&deflect their blasts; plus, the boy practiced pencak silat, an Indonesian martial art that became a great asset for him on both the virtual&real world, making the toughest bullies not want to pick a fight with him. In addition, he could augment his speed whenever he feels like sprinting, as well as triplicate himself to throw off his opponents. Although his friendship with his roommate started off rocky, Stern eventually became best friends with Della Robbia. To Stern, Aelita is like a younger sibling, with him occasionally protecting her from danger&calling her “princess.” There are many times when Jeremy gets impatient with Stern, especially his tendency to withdraw himself, but he knows to trust him to come through in the end. Stern has a romantic attraction to Yumi based on observation from a distance&repressed admiration. Even after sharing their first kiss, the two promised to keep it a secret&their relationship never really progressed, despite their feelings are evidently mutual. Stern has the habit of getting easily jealous whenever he sees Ishiyama with any guy not named Belpois or Della Robbia, becoming overly competitive, which usually annoys the girl, who often retaliates by suggesting Stern to do something about it, which makes him even more angry because he is too stubborn to admit his feelings. Despite their hostility at times, the two care for one another very much.

Just look at this photo and say one more time that they can’t act. This is the scene after they held hands (which was improvised). Yumi is looking up with a dreamy sight probably thinking about Ulrich and the situation happened before. The same with Ulrich. He’s looking down with a smirk on his face and he’s probably also thinking about Yumi. This photo is just perfect just like their acting in this scene.