Notes:

To answer your question: yes, that is goat monster!Frisk on the left. In this alternate universe, Frisk offered half of his SOUL to save Asriel. While they are both alive and well as a result, Frisk is transformed into a goat because half of his SOUL came into contact with the remaining traces of Asriel's own or something like that. Frisk does not seem to be bothered by the transformation at all (are there any characters in a transformation comic who do freak out after losing a form they were so comfortable with?)
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