They were apparently her favorite flower and she is constantly associated with them in her many of her scenes, there are daisies hidden in the background somewhere, her coffee mug has a daisy on it, the cards she gives John have daisies on the front, John gave her a bracelet with daisies on it for an anniversary ( which he keeps on his bedside table after her death) and the puppy she got for him was named Daisy (upon learning this, John says Of course). She was so great in-fact, John goes the extra mile in destroying the Tarasov Crime Family for killing the dog she left him and selling his life to the High Table just so he could keep her memory alive.
Flat Character: The series began at her funeral and all we know about her is that she died of an illness and that she was so wonderful she inspired the most feared assassin in the world to retire.Its also not entirely clear how much she knew of his other life in the sequel, when Gianna D∪ntonio asks John what Helen would think of him when hes forced to return to the old profession, he remains silent. That being said, John became a very different person around her, to the point where he actually left the criminal underworld to start a new life with her (hes also generally a Nice Guy anyway unless youve pissed him off).
She was Happily Married to John freaking Wick.