Addiction, compulsion, crutch. Dexter Morgan called his a "Dark Passenger." A cute nickname or not, it defined who he was as a man from the minute he acknowledged and accepted it, setting down a clear and distinct path that made him one of the most unique characters but had him calling himself a monster. Dexter never pined for "normal" because he never believed he had a shot at it-- because he never believed he was human and therefore worthy of it in the first place. But all of these years later, through time and relationships and exorcising demons the only way he knew how-- the only way he was taught how-- Dexter has come to want something bigger and better than a solitary life. Whether or not he can actually have normal is neither here nor there. His insistence on going after the Brain Surgeon proves that even though he may have a dream now, old habits don't just die hard, they may not die at all.
If I had my way, my perfect ending for my favorite show, Showtime's Dexter would see the man himself acknowledging just how much he lost out on by succumbing completely to his compulsion at the teachings of Dr. Vogel. In what he thinks and perhaps hopes would be one final kill before he heads off to Argentina with Hannah and Harrison, Dexter would strap Vogel on his table, surrounding her with photos of his younger self. He'd kill the woman who killed his chance, and then he'd set off. He'd dump his kill tools in the water along with her body. But the show wouldn't just fade to black with this odd but still happy family waving at Deb from an airplane window. Instead it would open back up with a final scene, a few months in the future, to see Dexter once again taking notice of someone who might be worthy of his table, this time by the Argentinian water rather than Miami. He's living his nice, normal life, but his old demons can't help but creep up. Vogel didn't make Dexter something he wasn't, after all; she just gave him a justifiable and safer way to give into his compulsions. This time, though, he's actively trying to fight them, and whether or not he'll succeed will be a story about which we'll just have to wonder.