Frustration.
The term was the one that Eren had to deal with very often lately. And say that was not happy about it was not necessary, the tension on his features could speak clearly. It was almost noon and the shifter was still trying to defeat his superior, with the naive hope that was possible.
Come on, Rivaille was the most powerful soldier of the time but had to have some weakness, it was not invensible. And due to the angry that Eren felt at the moment, not only by this act but the attack of jealousy that committed against him again, the younger was determined to win on this training. Yes, bad mix to someone with his temper.
And probably could wonder where the other member that usually helped were, well they had a few things to take care, so the Corporal was the only one willing to give him a hand for now, since was also the most closest.
Spat to the side the blood that was accumulating on his mouth, in consequence of his own mistake, wiping any red trail that could left with the side of a hand, emeralds filled with fire observing at his adversary, transmiting with a simple gaze how much wrath was covering every corner of his interior. A leg moving to impulse himself up and retake the original position, on his feet, getting ready to continue and execute a new attempt reach the older and overthrow him.