Stewart

hmmm maybe a psychiatrist who seems to be getting children clients for some reason and can see their imaginary friends because they can still see their own since usually, you're not supposed to when you're a grown up...

he's had his friend for so long and they get on well with the children too and their friends.
Idk if I want an adult to come to him with this type of ordeal and it's negative or if I just do daily things with img friend instead...I mean could be both.
if they meet this other adult person what if psychiatrist friend starts fading away
The other adult is just an imaginary friend snatcher/eraser.  

The adult that comes in could be the imaginary friend but in real life or something but I'm unsure.