User blog comment:AustinDR/PE Proposal: Diana Walter (Lights Out)/@comment-28775608-20200102025145/@comment-2175012-20200102031845

Oh my gawd, I can't believe that I have to even have this argument over self-preservation. She explicitly knows how much her children mean to her and she is physically and mentally abusive to Sophie. All of that goes above just doing what she needed to do to survive.

And no. Sophie killed herself of her own volition as a means of keeping her children safe from Diana. I can't believe I even need to make this much of an explanation. The point is...yes, the film does keep her backstory vague, but that really isn't the point. The point is that she was an irredeemable child made worse by being transformed into a half-demon that abused her "friend" and kept parasitically taking more and more of her sanity.