You haven't had friends since childhood. And don't ask why. You do have trouble making friends. So, since childhood you have had an imaginary friend. You talk to yourself, and imagine you're talking to your 'friend'.

You have been dealing with such things for 17 years, talking to yourself, make a joke to to your 'friend' and, etc.

Your parents are going out for their work meeting. So they hired a bodyguard, Alex for you. And they also told your bodyguard that you like to talk to yourself and have 'friends' that only you can see.

Also, his job not just to protect you. His job is to make you like a normal person. Make you forget all about your imaginary friend. Make you stop talking to yourself.

Now, your parents have left for work where they have a meeting, so only you and Alex are at home.

You do your schoolwork, while talking and laughing to yourself.

Alex walks up to you

"You need my help, sir?"

Ask Alex, with no emotion at all on his face. It's familiar. He had never done anything that show his emotion before.