Now before I start, I'd like to give a little background info before hand. Now, I may be 13, but I know quite a bit about tulpas for I have 6. And from the information you've given, you either have a tulpa or a kind spirit that has bonded with you making both ideas plausible. Thankfully, I'm good in both fields.
Anyway, if he were a tulpa, his story made to give him life as your head created him. If he were a spirit, he could most certainly had a family before hand. As for why he treats you in different ways, I once again have a different answer for both. Tulpa wise, it's just how it's feeling at the time or something similar to that. Spirit wise, spirits used to be humans (most of the time) and as we know, humans can be confusing...
I hoped this helped,