That one dieci background girl with glasses one day getting pissed off at Rodion eating snacks at the library so much, that she takes her to her room and proceeds to do a 12-hour hatesex pegging session. Edging + different sex toys (beads, vibrators, etc) included. After they're done though, despite it being a hatefuck (or at least that's what she convinces herself about) the dieci girl still makes sure Rodya sleeps well and leaves her her favorite extremely specific and hard-to-find dessert near the bed.
Since that day Rodya still eats snacks except this time she doesn't even try to hide them and even intentionally loudly eats them in front of glasses girl so that she gives her another "punishment".