The word reassurance comes from the verb reassure with the noun suffix -ance that describes an action, state, or conditio.  Reassurance was initially used to mean a repeated confirmation, a renewed pledge, or a financial term for a second insurance policy against a risk.  In 18/5 the emotional meaning of restoring someone's courage, certainty, or confidence became widespread. 

The noun "reassurance" was first used in English in 1611 in the writings of John Florio, a linguist and author, according to the Oxford English Dictionary (OED).  The verb reassure appeared slightly earlier in 1592, while the adjective reassuring emerged later in 1753.

Reassurance in storytelling provides emotional safety and reduces anxiety, helping audiences process complex realities and feel less alone.  

Why Reassurance Matters:  
Reduces Anxiety: Stories that offer comfort or a predictable structure help lower stress and calm the nervous system (insights via Headspace).  
Validates Emotions: Reassurance through narrative lets readers know their struggles are shared and normal.