Aerin lived in the First Age from 473 to
496. She was an Adan
of the House of Hador, and in close kinship to Hurin
dwelled in Dor-lomin, and when the Easterlings invaded Hithlum, she was
taken unwillingly as Brodda's (an Easterling) wife.
When Turin returned to Hithlum from his life in Doriath to find his mother, he found Brodda and threatened him if he did not tell him where Morwen had gone. Aerin told Turin that she had gone to Doriath to find Turin, and in his rage, Turin slew Brodda and many of the Easterlings around him.
Reference: The Silmarillion