That scene. When Joo seokkyung bangs her own head on the mirror and screamed “It hurts dad” I think it’s because she got traumatised when in season1 Joo Dan Tae abuses her.
Annie and eunjo were in a relationship. Shaxx leader snitched on eunjo and annie’s life starting to collapsed which cause her to suicide, and on the day she suicide, eunjo went missing for years. There were problems with the 2 groups, ( shaxx + sparkling ) they are rivals to ep 7 or 8. Everything is fine at the last episode. And eunjo ws alive this whole time. ++he also showed up on last ep and perfoms😃 happy ending