after leaving the ruins and killing everyone inside

You yet again appear in Snowdin town's forest

You expect to meet two skeletal Bros here

After a branch under your leg breaks without you stepping on it You turn around on reflex

But instead of nobody you see Sans, Sans the skeleton.

But...

His face...

Suddenly he starts to speak on Russian

"Да да, не переживайте. Вы из другого мира." "После вашей смерти вы проснётесь там где в последний раз проснулись."