Effie Trinket is the pink-haired prim and proper escort for the District 12 tributes. She's a Hunger Games administrator, and her character represents the wealth and power of the government. She's also, of course, a rather silly woman who places a good deal of emphasis on etiquette and propriety. In this sense, she is a comic, rather than a threatening, character. She is a token of the Capitol's frivolity and excesses.
As Effie hails from the Capitol, she views the Hunger Games merely as a competition – and a source of career advancement – rather than as a brutal death sentence. As such, she's excited to have tributes who might actually win this year. While Katniss finds Effie rather irritating, she does have a kind of grudging respect for what she does, as Effie does do her part to round up sponsors and rein in Haymitch the best she can.