Also, when he was setting up Terezi's confrontation with Vriska, leaving her all those clues and bodies and stuff? I totally read that as sober!Gamzee's idea of flirting. (chica likes murderdrama? I CAN MOTHERFUCKING DO THAT.) They're not sharing much screen time for that bit, but I think it totally counts as meaningful interaction.

...I am definitely in the "Gamzee's actions are never random" camp ("the most important character in Homestuck," the narration told us, after all). ^^;