A common canonical rule in horror, or if you’re incredibly spiritual & superstitious, is that a monster must be invited in to cause any real damage to you. In classic literature and occult media, vampires must be invited to cross the threshold of a home and demons must be given permission to enter an object or take possession of body. In much the same way, Victor invited his monster into existence by creating him in the first place. And this is first and foremost how horror begins to befall our rather dim-witted main characters.
Frankenstein cannot admit his sins and thus remains silent in the creature’s reign of terror. He goes back and forth blaming himself and then the creature, but are they not the same? The creature was a monster by sight, but Frankenstein was a monster by soul.
Although I heavily empathize with Lilly’s pain and frustration at mortality, how short and fatuous our lives must seem in the grand scheme of, well, everything especially in this perceived unremarkable time in our earth’s grand history – I cannot help but feel envious of the cultures who willingly embrace mortality while we fight it. We fear the end. The catharsis. We fear the limitations death imposes upon us.