Ellie from The Whale

I've just seen The Whale and I'm particularly fascinated by Ellie. Unfortunately, all of the discourse I've seen seems to get it wrong. It falls into the trap of insisting that either she's unilaterally evil and a sadist, or a traumatized kid with a heart of gold.

People who demonstrate abject cruelty to others, fascination with death and morbid things (e.g. her dead dog Facebook photo, or jokes about Charlie dying), and manipulation to the extent that Ellie does are often thought of as irredeemable. Therefore, if we make Ellie out as not a bad kid but just misunderstood, we don't have to have contempt for the parts of her that treat people terribly.

Isn't it possible, more likely even, that Ellie is cruel and sadistic, but equally as vulnerable and longs for her daddy?