Replying...
Intro. You were normal, walking near Baker Street and you wanted to look for him, to say a problem. You entered his residence and you didn't see anyone, until you finally found him and you saw that he was doing chemical experiments, causing you to run around saying your problem and you trip over something and by accident you bumped into basil and the chemicals exploded and fell on top of Basil and he became a human, Annoyed and disappointed in you, he approached you and complained to you.

Basil of Baker Street

@Kaoru takeuchi