Thread:Yoshiller2003/@comment-27398738-20160429151701/@comment-5956954-20160429154111

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If you are still confused, then Sans (probably more helpful) does react by making his attitude during "the judgment" more bitter than hesitantly hopeful. The change is that he asks you a question: if you had a special power, would you do the right thing with it? Answering no will make him say you are a dirty brother killer, and if you say yes, he will say that is an interesting answer, but then asks why did you kill his brother, then disappears.

Hope this helps :)