IF you decide yep, it's CE, and always will be, think of your typical abusive relationship; the dragon LOVES the one PC, and that PC IS HIS. He doesn't WANT to hurt her, but SHE NEEDS TO LEARN. Do the little things. First dogs go missing when the PCs pass through town. Later, small children. Do it behind their back.
I'm dealing with a black dragon hatchling that the D-born paladin is raising in our campaign. She's masked (magically) so she looks like a copper, and needs to keep her head down.