appear

I appear in whatever shape you like, I appear as whatever person you want. As friend, as enemy, ...
I appear with any strength that you like. I talk any accent you like, I will take any personality you like. I will be male, female, maybe none of both. I will be child, I will be tree, I appear as anything you like.

Call me and I am your imaginary toy.

But whatever I do, it is (somehow) just me...