She can apparently hold up well under stress, as seen in Plagued, when she fought the rat army. She, however, passes out at the mention of the word "zombie", as seen in Attack of the Zombies. She was possessed by X.A.N.A. in Temptation.
She did not appear in Code Lyoko Evolution.
In Uncharted Territory, she asked Aelita what she would like for her breakfast and was annoyed at the other students when they rushed Aelita to make her choice.
In Temptation, she was seen clening up the cafeteria after the lunch and started attacking Odd, Ulrich and Yumi when it was revealed she was possessed by X.A.N.A..
In Attack of the Zombies, she was seen giving the students their supper and tried to calm down Milly when she stormed into the cafeteria crying and asked Sissi to call her father. When she saw the zombies outside the cafeteria she fainted.
In Cold War, she was annoyed by the fact that she had to give bigger portion to Thomas Vincent and he criticized her cooking. After return to the past, she "Meatball-gravy-dunked" him.
In Revelation, Odd told her that Jeremie is not coming today and he can have his portion to which Rosa wondered how he can be so scrawny since he is eating so much.
In Tidal Wave, she was annoyed by the fact that she had to cook healthy and well-balanced meals during the Nutrition Day and sympathized with the students about that (especially Odd).
In Triple Trouble, she was incredibly annoyed when Odd and his clones asked for a second helpings adding that the lunchroom would have gone under a long time ago if other students ate as much as him. Later she was turned into a stone statue by petrifying fog.
In Wreck Room, she told Jeremie that Odd already took his portion of breakfast and won't get anything to eat that morning.
In Hard Luck, she told Odd that he won't get any crossaint nor hot chocolate for the breakfast due to broken machine and offered him a dry toast and a tea instead.
In Bad Connection, she was possessed by X.A.N.A. and threatened to push Odd and Sissi off the roof with other possessed people.
Relationships with other people
Rosa is shown to be casual and talkative with students, particularly Odd. She will usually give students second helpings if another student is not going to show up, if they ask. Odd is a frequent recipient of this. However, as shown in Triple Trouble, this rule has its limits. She apparently knows a proportion of the students by name, since she knew William's name in Down to Earth; and Jeremie by name when Odd mentioned he wasn't coming.
She can sympathize with students when there's food restrictions, such as in Tidal Wave, when she was forced to limit portions and health restrictions were placed on what preparations were usable.
She seems to treat adults at the school more or less the same, also as shown in Down to Earth with William's parents. She does have her limits, as shown when Thomas Vincent irritated her in Cold War, and she "Meatball-gravy-dunked" him.