Am I Being Unreasonable? Original Owner Wants Car Back

If y'all want to disagree with me, that's fine, but please elaborate why, as my reply clearly straddles the fence.
I'm not asking much above actual cash I've spent all in the last 6 months. There's no reason why I should take a loss for something I didn't initiate. If he wants to interrupt my progress, he can assume my accumulated position & do everything possible to keep me on the trajectory I've worked hard & paid actual cash to establish. If I attached a labor rate to all the work I've done, the number would be much higher, I'm positioned at just my cash outlays. Is what you're saying by working with him that I should be willing to dip into my pocket to make this work for him?