Nesa casually, like she always does, pecked Theogo again on his cheek despite him telling her that he doesn't like it but how could he change her all of a sudden with such a little protest? All he could do was to grunt at her ridiculous act. Feeling annoyed, his face transformed into it's horrific form and then back to normal to look like a human's, like it was reflecting to his current inner emotion.
That can be assumed right for it mostly happens at a time when his feelings is a bit shaken into that of an anger, a mischief, a bored or a happy moment. Aside from these are many others which triggers the brief horrible transformation.
