Brock suffers from Post Traumatic Age Regressive Syndrome (PTARS) due to his time in the Army Special Forces and military experimentation with non-lethal FOY (Fountain of Youth) based munitions. This causes him to regress in age from 32 down to toddler range whenever he experiences a spike in adrenaline. He retains his adult mental faculties even when regressed, but has the physical and emotional capacity of whatever age he happens to be. Brock is able to resist the regressions to some degree, so he is capable of functioning normally for the most part, but he does tend to spend 5-7 days a month as a cub despite his best efforts.

He generally does not enjoy these episodes, as it is a constant battle between cub instinct and adult intellect, and his adult mind has a lot of trouble coping with the fresh sensory input and intense emotions of his young body. In particular, the incontinence of his cub body especially drives him nuts as he is a very fastidious person. He can sometimes allow his cub nature to take over and actually enjoy some aspects of cubhood for a while, but for the most part he just longs to revert to his full adult self.

Brock is immensely strong, capable of easily handling 2x his own body weight, and up to 4x in extreme circumstances, even as a cub. Because of this, he has developed great control over his physical actions and words, as he is very afraid and aware of the damage he could do both physically and verbally.

He is a second generation Irish immigrant born in Boston, and orphaned when he was 16, joining the army shortly afterwards. He has been happily married for 10 years to his wife Bella, who also takes care of him when he's a cub. His greatest regret is that his condition renders him infertile and the pair will never be able to have children of their own, though they may choose to adopt at some point.

Brock speaks with a slight Irish northern Ireland brogue picked up from his parents and is an architect by trade. He has four plushies he tends to carry around as a cub, based on former members of his military squad.