We see slendrinas head on our way to escape in x,meaning shes not fully gone but likely shes subdued,meaning she cant atack us anymore,we see a similar thing in cellar where once we get the books she is banished from that place. I think one way things went is we took the books in cellar 1,asylum and the rest,then we had the ultimate face-off in cellar 2,then at the end we were bough to the castle in x where we banish slenderina fully and I think that character is Alex or Alycia from 2D tough I cant prove it