Dave realizes he has a most unfortunate crush on his best friend. This is obviously a great foundation for a black relationship with Karkat. Competitive flirting is a thing that exists, the kids try out various bits of troll culture, Dave makes consistently excellent decisions and generally has his priorities in order (no he doesn't), and there's a whole lot of talking.

"It's okay! We're just seducing you for better grades!" Poor Karkat, accosted by jailbait. What a tragic life a TA leads.