Tartah and Coco’s being weirdly not mad at the people they love for the mean things they do to them
The most obvious example is Coustas when he showed up to attack them. Coustas very much had the right to be angry at the whole hiding magic and letting him think he was just born unlucky, but both Tartah and Coco could also have been mad. They are both kids and would have been punished if it ever got out they taught him magic, plus they both did their best to help him despite that. However both of them were instead very apologetic and took the full blame for everything that happened.
Another example of the truth spell incident and Tartah joining the brim caps. Both Coco and Tartah had good reason to be mad at the other. For Coco, having a truth spell used on her and then being ditched with both her friends joining the brim caps and for Tartah, having to use the spell on someone who he thought would be honest to him in the first place and then having to join the caps alone because Coco didn’t come. Instead, after the truth spell Tartah immediately offered Coco fo join him and even whispered to her about how he doesn’t like the caps like they were still good friends. And after Tartah left when Coco broke down she was only mad at herself for failing to save anyone, to save him.
Another example for Coco is her not holding any feelings towards Agott (she didn’t even really want an apology)