The Librarians' Cassandra is very aware of her limited life span, but viewers should worry that writers will off the synesthete casually.

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All Librarians face death on a weekly basis, sometimes twice by Friday, but Cassandra (Lindy Booth) is in a slightly different position than the rest of her fellow librarians-in-training.

Cassandra's brain tumor, or, as Ezekiel (John Kim) is fond of calling it, her "brain grape" may provide the math/science expert with an extra level of comprehension, but it also means death is an ever present concert for Booth's character.

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"We did the research and picked a tumor that moves slowly," said executive producer John Rogers, according to Zap2It. "It's slow-growing enough that it's been hanging over her head for a couple years, and it's not going away. There's no fake threat of 'Is this the week that Cassandra's tumor kills her?' ... But there are episodes where Cassandra's gravity with that is a plot point and it does make a difference [in her character]. She's very aware of her own mortality. It's not a thing that goes away."

Find out more when The Librarians airs Sundays at 8 p.m. ET on TNT. Click the video below to see a preview for the series' next episode.