Hey Richelle, Adrian was twenty-one in Frostbite. That makes him twenty-two when Bloodlines started, unless we went back in time somehow and everyone retained their memories of the past year and you just failed to mention it. 
 I'm not sure what's worse, if all six Bloodlines books had continued in this vein or the tripe we got in the form of Sydney "Mary Sue" Sage and Adrian "I Underwent a Personality Transplant" Ivashkov in the published Bloodlines series. 
 The world may never know.