A Brief Story

Let me tell you a story...Let me see, how would it started?
OK, maybe like this: few years ago, he was just a little boy.
He had to obey every order which his parents gave him. He always had a lot of dos and don'ts: do your homework, don't play too late, make sure you are safe, don't do that trick again...Time flies, he grew up. He still did every thing he was asked to. He obeyed every rule. He became a normal person, who had a normal black cat.
But one day, the black cat got lost. He didn't know where it could be. He tried hard to find it. However, after his searching, he never found his little black cat. He felt dissappointed. He went home alone on foot, then he took a shower. After that, he cooked some horrible food for himself. At last, he finally crashed.
He lost his cat. The little black cat, which he got on his 21th birthday. After 5 years, it finally decided to get lost. And after so many years, he finally became an ordinary man.  He was asked to quit from his job because of poor performance. He was nobody but a total freak, obeying every order from everywhere, doing routine work within every rule.
One day, he was found dead in his appartment. His neighbour at last couldn't bear the horrible smell which was spreading from his apartment. She called the police, complaining about the unpleasant smell. After she found out about her neighbour's death, she did something. She took a photo of the dead body, and posted it onto social media...
"MY NEIGHBOUR WAS KILLED!" she marked. Then a little black cat went out, from her door.

Well done.  The topic was a little unsettling but the English was pretty good. 

I'm not sure what you mean about 'becoming a normal person'  or 'becoming an ordinary man',  was he somehow out of the ordinary previously?