He was fighting Betty as they stopped Betty looked annoyed because she wasn't getting anywhere until she got an idea

Betty: hey frisk! Do you mind if I bring an friend! I think you know them.

Frisk: what are you talking about??

He was interrupted by something hitting the ground bring dust every where,but his heart stopped soon when he seen who it was...

Frisk: ..L-Love?

YOU WAS CORRUPTED.