Hem is a sewing-talent fairy who is seen several times in the book series. She has plump cheeks and light blond hair, as well as a blue top with a frilly pink skirt, pink flip-flops, and a pink flower in her hair. Her name is likely taken from the verb "to hem", in which a cut edge is folded twice over, and then sewn into place, preventing it from unraveling.
In the books
At the end of A Masterpiece for Bess, she appears. Hem has sewn a peony pink frock and shows it off. This is a new fad, following the fad of Bess's artwork. Hem gets overwhelmed when the fairies crowd around her, wishing for a dress just like hers.
In this story, Hem realizes that Rosetta is annoying all of the sewing-talents with "suggestions" as to how to improve their dresses. And so she concocts a plan to get Rosetta out of the way- tactfully suggesting that the garden-talent make her own dress. Excited, Rosetta thus focuses on her own task instead of bothering the others with occasionally hurtful advice.
In Silvermist and the Ladybug Curse, Fira and Silvermist followed her to see if a pin would fall, so Silvermist could have good luck. While in the sewing room, Silvermist caused all the pins to go everywhere. Hem politely informed her that the sewing room is a bad place for her to be with bad luck.