Brian Caruso is the son of Jack Ryan's sister and her husband Mr. Caruso, twin brother of Dominic Caruso, grandson of Emmett Ryan, nephew of Jack Ryan and Caroline "Cathy" Ryan and cousin of Sally Ryan, Jack Ryan, Jr., Kathleen Ryan and Kyle Ryan. Brian was a Marine Corps recon and intelligence officer, reaching the rank of captain before joining his brother Dominic and his cousin, Jack Jr in the new Agency in The Teeth of the Tiger. He was killed in Dead or Alive.