What do you mean with behavior? People are still discussing how it spreads.
The latest news is it travels as aerosol and that in badly ventilated rooms keeping 1.5m distance is not going to help much. And also that the amount of virus particles you inhale determines how sick you get.
So it is only predictable when we know how it is growing exponential.
The still ongoing discussion about how it spreads creates uncertainty.
Covid is a simple as any of the things we meet in daily, in aggregate, as simple as rain or dirty. The behavior in detail of any of these things is incredibly complex, of course. The forms rain takes are distinctly complex but is nearly falls roughly downwards and gets things wet (exceptions to everything, of course).
People have more incentive to look at the details of Covid 'cause it's much deadly than rain or dirt. But even more, lots of people use Covid's uncertainty to argue against any mitigating measures they find inconvenient - and that part is kind of despicable.