Hmm now reading the translated version I think AnastaciahgGac (whatever his name is) is having an inner battle between himself and another person (the previous emperor who was mocked by Lucas) hence why his eyes switch between red and blue. I think when his eyes are blue it’s the real Anastaciius as he patted Jeanette (when they were blue) and he was longingly looking at his hand. When his eyes are red, it’s that other evil dude.
Moreover, I think the part where his mother is angry and insulted because she’s not capable of using magic is significant. Perhaps Anastaciousus was not able to use magic either (probably was unable to inherit magical powers??) so he had to use black magic yadayada and somehow made a deal where he shares his body with that previous emperor(?)(the one Lucas didn’t want to teach) CAUSING HIM TO BECOME EVIL and yah
This is just a guess of mine, sorry for the terrible grammar my brain is fried from school teehee