Naruto Primer: Aburame Shino
Revenge
Like every other genin in the world, Shino's biggest goal is to become a chuunin. After all, he wouldn't have entered the chuunin exam if he didn't want to be a chuunin.
When it came to the test portion of the exam, Shino had the perfect strategy to get the answers. He sent his little bug friends to learn the answers from other people and then they returned. If the test hadn't been irrelevant, he would have passed with no problem.
Then, the Forest of Death was ALL him. Not only was he the one who got the second scroll for his team, but he was the one who insisted that they go to the tower as fast as they could without bothering to get other scrolls. He had to brave the Forest of Death, a place where MANY genins died, in order to win his chuunin hood.
Even worse! He had to fight some insane guy with air valves in his arms. It's not like he was a challenge or anything, but he still had to do it and many bugs lost their lives in the process.
In loving memory of the bugs who lost their lives…
In the month period of time between the preliminaries and the actual chuunin exam, Shino did nothing but work his butt off to train as hard as he could, learning all sorts of crazy new strategies and ways to surprise his new enemy.
Then…THEN…when it was FINALLY his turn to show off his mad skills, all his termites ready to eat away at the wooden puppet and clog the puppet's joints…
But Kankuro forfeited. HE QUIT!! Shino didn't get to show off his skills!!!
It was okay at first because Shino figured he could just fight against Temari and beat her so bad. Then he would fight Naruto or Sasuke and WIN!! It would prove to everyone that bugs ruled.
But that never happened. The exam was cut short. And Shino never got to show everyone what he could do. Therefore, he did not get to be a chuunin even though he could have potentially been one of the people promoted! BUT NO!! KANKURO HAD TO FORFEIT!!!
Now he had to take the chuunin exam next time! And take the written test next time! And brave the Forest of Death next time!! And go through the preliminaries next time!! And FIGHT IN THE TOURNAMENT NEXT TIME!!! IT JUST WASN'T FAIR!!!
Of course, Shino didn't really show his anger or sadness, but it was there. Shino was out for blood. He was ready to kill Kankuro.
He did…KIND OF. But still, Shino was unhappy that his revenge wasn't fully complete.
You don't see this in the manga or show, but Shino has been harassing Kankuro lately. Under the guise of night, Shino has gone to Kakuro's house armed with rolls and rolls of toilet paper and tossed them all about the yard! Then, with many different colors, Shino would spray paint things like, "QUITTER!" and "FORFEIT!!" and "CHUUNIN!!" and "IT'S YOUR FAULT!!!" and "DIE DAN DIE!!!"
Except he wrote 'Kankuro' instead of 'Dan'.
I bet you didn't know this but a chapter was omitted from the manga in which we journey into the abyss that is Shino's room where he has many voodoo dolls of Kankuro scattered about his room filled with needles and pins and all sorts of other unnatural things!!
As you can see, Shino is not quite the calm collected one we have known to love.