That bird is not acting sweet or standoffish or aggressive on purpose. Sure, it may be naturally sweet or standoffish or aggressive, but, even more, it's a flock animal and is aware of its place in the flock and, even more, dedicated to preserving and improving its place in that flock.

Plus, the bird has nothing to do all day long but watch you; it's got a pretty good handle on you. It knows what strikes you as sweet and what frightens you and how likely you are to be nice or mean or take a place ahead or behind in the flock hierarchy.

So the bird is working, working to get what it wants out of you. Don't doubt for a moment that it's smart and dedicated enough!

But you can use this manipulation to your favor as well. Try and think ahead and figure out what the bird wants, when it's behaving undesirably, and fail to deliver that outcome. So long as the bird doesn't get what it wants, it'll try a new strategy, one that may be more positive.