Board Thread:General Discussion/@comment-32070780-20170805155555/@comment-3152371-20171114230321

I think it's a hint that Chara didn't literally destroyed the world in the Genocide Route.

As written in the Player article, one interpretation of the Genocide Ending is that the place where Chara meets the player is in the Frisk's inner self, where Chara kills the player and takes over the protagonist entirely. However, maybe Chara can't pass the barrier and leave the Underground after taking over Frisk.

That explain the sudden interest of Chara to gain the protagonist's SOUL in exchange of a True Reset: Chara plans to leave the Player destroy the barrier and then take over Frisk, avoiding being trapped again.

The Neutral Leaderless Ending and Genocide Ending have similar background sounds, what can indicate that they happen in similar places: a somber Underground, from where Sans calls from and Chara is trapped in, respectively.