Deadpool & Wolverine: 23 Easter Eggs & References Explained
12. Cassandra Nova's Backstory
Deadpool and Wolverine offers up a relatively curtailed explanation of Cassandra Nova's absolutely wild backstory, possibly for pacing rather than content reasons.
She reveals that she's the twin sister of Charles Xavier and that he attempted to kill her in the womb as in the comics, though neglects to mention what happened next.
In the comics, Cassandra and Charles' in-utero battle led to Cassandra being miscarried by their mother, but her flushed genetic material clung to a sewer wall for decades before rebuilding into a human form.
Given some of the transgressive madness in this movie, it's tough to consider that this expanded backstory went too far for Deadpool, so it's more likely a case of expediency - of quickly setting up Cassandra's past and moving forward.