Let me tell you a story

My name is...well...I don't exactly have a name...
He gave me a name when I was younger and then he forgot about me.
His name is Gunner by the way.
I'm his demon...and that's not a bad thing!
Demons aren't exactly as bad as you think they are.
Anyways, he called me "Duck".
I was his "invisible"-friend...till the sixth grade.
...then he changed, and I never saw him again.
Till this year.
He needed help and I was there.