Agent Boo is an agent with The Agents.
This is a group of specially chosen teenagers, seniors in the school training such to-be-operatives. The Agents built Space City, the very center of the Multiverse. From the Aerie, Space City's highest tower, the Agents kept law and order across a thousand parallel worlds. These are individuals who head to any troublespot in all those differing environments to keep the peace and protect the innocent, and sometimes losing their lives in the process.
Each of the new Agents is picked from the Senior class by the "companion" they will work with during their career. These companions are animals of various types who are very intelligent and can talk (sort of like a witch's familiar) and act as assistants and advisors to the Agent during those assignments.
Every newly chosen Agent is at the end of their training, adult and skilled enough to put their lives at risk for the betterment of everyone. Well, up until today.
At the yearly choosing, the large auditorium was filled, as usual, with all the younger students not yet ready, brought to watch a special graduation ceremonial choosing. So far three have been chosen, each one apparently around 18 years old. Then came for time for the last companion to choose: Pumpkin, a cat. "Look, I can't do this anymore," he moans. "I'm tired. I'm bored. I need a vacation ... And none of these kids have ever had an original thought in their lives. I'm outta here." With that he started to leave. He was most of the way out when the Supreme Agent reminded him what would happen if he did not make a choice. We don't know what that is but by Pumpkin's response, it isn't good.
So Pumpkin had to choose. And being the "you-can't-tell-me-what-to-do" fellow he is, he leaped into the seats and chose the very first person he came to (at least that's how it looked to me).
That person was Boo. She is a fourth grader. Still way young in her training. Nowhere close to being ready. And she is small. Wee. "The littles, most picked-on girl in the fourth grade".
"Mr. Pumpkin, I don't think I'm right for this. I'm not smart or special or anything," Boo whispers to Pumpkin, "or even very big."
"I know," said the cat, "And it's gonna drive them bat-crazy when you do just as well as them."