A childhood belief about imaginary friends

i guess i had an imaginary friend. he wasn't very friendly though. i saw him a lot more when i was like three. he never told me his name no matter how many times i asked. he always said 'sir' was fine. he was pretty tall and skinny and always wore a suit. he looked pretty normal except he didn't have a face and when he talked to me, i heard him in my head. we never really played games or anything though. he tought me how to draw and how to play the piano. i remember he never let me touch him. every time i got close he'd vanish but i'd hear him say to me in my head that if i tried that again he'd leave me forever. i would see him a lot in my dreams too. he would always call me by a different name in every dream. once he called my by my father's name in a dream and when i asked him why he called me that, he said to take it as it is. what does that even mean?? i'm fifteen now and i see him less and less. the one thing that bugged me was he had people of his own that he could see and i couldn't. he would talk to them all the time but i couldn't see or hear them. i thought it was a game but he said it was just work. i guess even imaginary people need imaginary friends of their own.