Kieran is a potential guard for the caravan leading brahmin through Big Bend Tunnel during the event Riding Shotgun. He mentions to Eugenie that he has attempted to find a different line of work many times, but it has never worked out. He is described by others as being untalkative and moody. None of Kieran's blood relatives are still alive; however, several kids from an unnamed homestead are part of his his adopted family,[Non-canon 1] including Hannah, who calls him "Uncle K." He is an "old associate" of Vinny Costa, though any details of this association are not made clear.
The following is based on non-canon behind the scenes information.
Kieran's writing was contributed to by quest designer Carl McKevitt, who created much of the Blue Ridge Caravan Company.
On the Bethesda Game Studios official Discord, Carl clarified that Kieran has no living blood relatives, and that his children are adopted.[Non-canon 1]
Kieran's face was initially much younger, with black hair and the "Anchorage" hairstyle, before he was aged up to match the voice actor. As Kieran was the first guard implemented during development, his actor template was duplicated to Aries, who kept the old face model, just obscured by the mask.[Non-canon 2]
Carl also stated that Kieran's name is a very subtle nod to one of his favorite video game protagonists, even if Kieran's final appearance in-game makes the reference "practically non-existent." While he did not reveal who exactly this protagonist was, he stated that there were some clues left behind, including Eugenie's line about past jobs.[Non-canon 3]
End of information based on non-canon behind the scenes information
Kieran watching with binoculars if he appears at Big Bend Tunnel West
↑Eugenie: "Ever consider a less dangerous line of work, Kieran?" Kieran Kennedy: "Yes. Many times in the past." Eugenie: "So... I'm guessing it didn't work out, huh? I don't think I could picture you doing something more mundane. Kieran the fisherman. Kieran the bar tender. Kieran the... professional singer." Kieran Kennedy: "It did not." (Eugenie and Kieran Kennedy's dialogue)