Board Thread:General Discussion/@comment-24100805-20160201152915/@comment-26133480-20171230204715

Frisk's muteness Actually, Frisk is shown in canon to not be mute:

Toriel calls and asks what the kid's preferece is: Cinnamon or Butterscotch. Since the phone given to Frisk by Toriel lacks texting capabilities, the only possible way Frisk could answer would be verbally.

Similarly, should a player use the "Talk" option during Asgore's battle, the narration will first say about quietly telling Asgore not to fight and the attempts to reason w/ him becoming more assertive the next 2 times.