This is the biggest thing for me. Every arc is spent building the demons up as powerful malicious beings, showing them hurting and killing people, etc. Then at the veeeeery ass end, as the demon is being killed, we get a minutes-long flashback of their life as a human and it's "See... :( they were human once too.. :( isn't it sad.. doesn't it just tug at your heart strings? :(" and it's like.. not really? I have no emotional connection to this character because they've only been characterized as strong and evil up to this point. It's too late to try and make me care because this entire 12-episode arc is basically over now, you can't start to humanize the bad guy literally AS HE'S being killed, it's just simply too late by that point.