As is apparent from the conversation with a dead high priest, Myra is smarter than Christano. If the Princess tries to tell Myra about Christano she will discover that actually Myra is aware of Christano doings, but chooses to ignore them. Myra loves Christano, and once Christano gets hurt she will do anything to save him, without giving a damn about "consorting" with demons.
Given how much "special skill" points Christano has, and the things the princess hears during their trip on a boat, Myra also apparently posesses some hidden artistic talents.
It is unclear how much credence can be given to Hyath's claims that Christano is ready to kill the princess. Indeed Christano is very eager to kill the princess if she decides to summon Hyath, but it may be only his religious zeal and foolishness - he did attack poor forest animals claiming they are evil spirits.
When the princess meets Christano again in Part 2 he is a changed ... person. Christano never was the brightest bulb in the box, but in the end it looks as though what was subtracted downstairs, as meager as it was, was added upstairs. The only bothering thing is that even changed Christano in the end leaves the princess.
Note: Never drink tea prepared by Christano.