She was mentioned in "Monster", where Quinn states to Zachary that Theresa can tell him what to buy for her, and then made four appearances in the next three seasons: "The Old and the Beautiful", "Daria!", "A Tree Grows in Lawndale," and "Aunt Nauseum".
When Lawndale High became a "loser school" in "Tree", Theresa is the only staff member who (albeit reluctantly) will talk to the Fashion Club, explaining that it's bad for Junior Five's image to have losers shopping there. She allows them to use "fitting room eight", the dreaded unpopular people's dressing room.
MTV's feature "Love is a Way Too Many Splendored Thing", a 'flipbook' of Quinn's admirers, has Quinn state that Zachary ended up dating Theresa. "Good riddance!", says Quinn, who really just has herself to blame.
Theresa in Fanfiction
She usually appears as a secondary character in scenes taking place in Cashman's. Stories with her include: