Her father was a playwright, the great-nephew of the songwriter Peadar Kearney (author of Amhrán na bhFiann, the Irish national anthem), and brother of the writers Brendan Behan and Dominic Behan.

[5] Behan trained first as an actress at the Central School of Speech and Drama, and appeared in numerous plays and on television, including a role in Eastenders and productions at the National Theatre.

[6][7] In 2011, her play Brendan At The Chelsea was produced at the Lyric Theatre, Belfast, with Adrian Dunbar starring.

[8][9][10] The play was published by Edinburgh University Press in 2014, and Behan appeared in an RTE television documentary 'Brendan Behan - The Roaring Boy', alongside Adrian Dunbar.

[11][12][13] In 2016, Behan premiered her new one-woman play 'Realtine / Noreen' at the Camden Fringe, Tristan Bates theatre.