I listened to the
companion cast for episode 4x08, and I'd just like to say that it's very relevant to our interest.
Felicia explicitly states that Fawkes genuinely cares for Codex. That he really likes her. And she also says that she had Venom expose the fakeness of their relationship, because the only other option was Fawkes, and she didn't want him to do that, because he liked and respected Codex too much to put her through that.
Also, Fawkes is being a jerk as a front he built to defend himself, as he grew up a giant nerd, and needed some sort of protection due to that.
Felicia, I love you. I feel like I can love Fawkes even more now, knowing all this.
Also, Kim Evey, the producer, revealed that Felicia loves reading bodice rippers. I think someone on this comm needs to write a historical AU for Codex/Fawkes in her honour. Fawkes could be a dashing high way man, kidnapping lady Codex for ransom. However, they cannot deny the smouldering UST. (Yeah, I'm not good at this.)