He fought Caprica for the right to kill Gaius, but granted him reprieve so that he could save the survivors from Three's nuke as they were leaving. Back aboard, he carried out the search for Earth from Gaius's notes and calculations; they repaid him with a bag over his head and near-murder. He never stopped hating Kara and Saul after that, even though their time on New Caprica was even worse than his. He tried to kill Gaius again, to hide his secrets, and eventually committed perjury to see him dead. On the Demetrius he followed Helo's momentary mutiny with one of his own, and lost a leg. He spent weeks in the infirmary, singing so beautifully; giving voice to something he had lost. Felix is Latin for a particularly innocent happiness: it connotes a luck in life, as in a felicitous coincidence. His parents named him for Joy. Now he's in his quarters, speaking to someone, smoking one last cigarette.
"Suppose a long time ago, it was... architecture. There was a year there where I scribbled floor plans on everything? Dining room table, patio tiles, rare books... Drove my parents crazy." Gaius asks how old he was. "I don't know, uh, eight, maybe? Nine?" Gaius is smoking, too; he can't take his eyes off the prisoner. "Tell you one thing, though, I had some pretty frakking amazing ideas. Restaurants shaped like food. Hmm? Top-heavy buildings... And stairways, every... Everything had to have a stairway..." Gaius smokes sadly, and puts out his cigarette. Felix pours him more ambrosia: "Spoils of war..." He smiles, happy in the final analysis, to be here, now. With Gaius. The only friend he has left. Gaius can barely drink. "When I was older, uh... Then it became medicine, and... Engineering, photography. I think I would've made a better architect than any of those, though. And then, I discovered science. And I ... Thought I was really, really good at it. Until I met you," he says graciously, obligingly, affectionately. Gaius tries to hold back tears.
Gaius leans forward, through the haze of smoke, and says his name, softly. Just once. "Don't," Felix nods. The intimacy is palpable. One more word and he'll break. "And please, no religion." Leaving aside the point that this moment here is all religion is really good for, what else can he give? He wants to do something we don't have a name for. It's something a Cylon could do, easy as thinking, but we do things differently on our side. How to connect, through all that history and salt and smoke, how to reach from one body to another and express that horrible, wonderful existence of someone else, that cuts through the loneliness that only humans know. This was Laura's lesson on the Hub; if Jake humanized Romo then this is all Laura's lesson for Gaius now. How to connect, how to just love somebody.