Mark rescuing Jeremy from the book group. Awesome and also about as heartwarming as the show gets.
Jeremy (VO): Fuck you. Mark's going in to bat for me! ... And he's really good at this! Unlike any game actually involving a bat.
Jeremy's Christmas stocking for Mark, which he has clearly spent a lot of time and effort on, and bought presents Mark would actually enjoy, by means of actually listening to Mark talking about what he's interested in. Slightly marred by the fact that Mark's stocking for Jeremy is a plastic bag containing firelighters and kitchen tongs.
Mark having British London make a counterfeit life coaching certificate for Jeremy, in a rare gesture of genuine humility and respect towards him.