Emma Chase is the oldest daughter of Randolph Chase and the cousin of Annabeth Chase and Magnus Chase.
History
Emma was born in Boston, Massachusetts. She presumably grew up in her father's mansion along with her younger sister, Aubrey. At some point in her life, her father entrusted her with the Othala Runestone as he saw her as his successor to the family.
Magnus Chase and the Gods of Asgard
The Sword of Summer
Although she was never mentioned by name, she along with her sister and mother appeared in the epilogue when Loki conjured up an image of her in Helheim.
The Hammer of Thor
She appears in a flashback when she and her family accompany Randolph on find the Sword of Summer in the Massachusetts's bay. However, a freak tempest caused their yacht to go overboard, causing her and her mother and sister to drown.
The Ship of the Dead
Whilst approaching Naglfar with Samirah al-Abbas and Alex Fierro, Magnus sees an opening to Helheim and hears the voices of Emma, Randolph, Caroline, and Natalie Chase calling out to him.