Board Thread:General Discussion/@comment-35951900-20181123220830/@comment-33613511-20181208142656

well, the common theory is that the kids given their souls back after asriel absorbed them all. like the monsters were.

Also, pretty sure undyne killed them, or other royal guard members. asgore is reluctant to kill you. he destroys the mercy button because he believes he doesnt deserve it, even though he didnt kill the other children, it was his plan, and he regrets it.