Board Thread:Fun and Games/@comment-27524978-20160317154321/@comment-27524978-20160411010822

Iku-P wrote: GetYourFix wrote: Fanon sans: Can have a tongue and fangs. You forgot... something else haha Oh I know! It's the glowing left eye right? Sans only uses it in the game when he's doing telekinesis, but in Fanon however, his eye glows the entire time while fighting Chara/Frisk!

That should most certainly be it!