They are conjoined twins, which means they are twins with their bodies bound together since birth; in this case, they are two heads in a single body; the right head being Elisa and the left, Eliza. For millennia, they have kept the same appearance: elderly women of unknown (though advanced) age, skinny with gaunt faces and purple-lined eyes, long pointy noses, crooked teeth and black hair in a tight top-knot. They dress according to the year/century they are in and lately they wear a black, long dress with two tall light grey collars and a blue pendant around each neck.
The Stitch Sisters are great deceivers. On the outside they maintain the facade of being simple elderly saleswomen, friendly to regular people. At heart, however, Elisa and Eliza are wicked, deceitful and malevolent: once they find a potential new member for their "Quilt Club", they slowly reveal their true nature. They are very skilled in bending others to their will and luring in their victims. The Stitch sisters are also very particular about who may join their club. They allow only women who have forgotten their families and lives and who are very good at quilting; this, however, may be a requirement of the magic process for the quilt to absorb their souls as it is the quilt itself who seems to make the decision of whether or not the woman is right. Ultimately Elisa and Eliza only care about prolonging their lives forever by continuing to trap the souls of women into their magic quilt.
The Stitch sisters have lived since prehistoric times. At some point they came into the possession, or rather the service, of an evil semi-sentient magic quilt. With power of the quilt, Elisa and Eliza have prolonged their lives for countless eras by trapping the souls of women into the quilt. They do this under the guise of a "quilt club." Their many travels have taken them all over the world including Egypt, China, Japan, Constantinople, and early American colonies. After centuries of stitching and collecting countless souls, the Stitch sisters' travels finally brought them to an old house in Nowhere USA, where they set up their home and quilt shop.
The Bagge Family is rummaging through fabrics in an ancient, dusty handicraft shop that specializes on quilting. The owners are the two strange, conjoined twin sisters named Elisa and Eliza Stitch, who live and work in their shop. Muriel wants to join the Quilt Club, as advertised over the cash register, and is fascinated with the quilt the Quilt Club allegedly have made together. But the Stitch sisters are not satisfied with Muriel's swatches, as they prefer to "make new memories." Muriel works her fingers to the bone to make the perfect example quilt, each time forgetting Eustace and Courage more and more, until she cannot remember him at all, which is the Stitch sisters' real scheme, and is now ready to be accepted into the Quilt Club.
The Stitch sisters arrive at the farmhouse with their quilt, and explain to Muriel that the only thing she needs to do now is to embroider a certain symbol on a block of fabric, and sow it into the quilt. Courage takes a picture of the symbol and scans it into the Computer. He researches the history of the Stitch sisters, and finds out, to his great horror, that Lisa and Eliza Stitch have kept themselves alive for hundreds, if not thousands of years by making unsuspecting quilt enthusiasts sow the symbol of everlasting life (the same symbol that Muriel is working on at that moment) into their quilt, thus trapping their souls inside it and sustaining the sisters' own lives. Downstairs, Muriel has finished her patch and is excited to meet the other members.
She is helped by the sisters to add the block to the quilt, and this is when she realizes that the real Quilt Club is the quilt itself, which is composed by the souls of dozens of previous aspiring members. The sisters chant a magic spell to lock souls in the quilt ("Weave believe belong, weave believe belong, leave the circle never, weave the quilt forever"). Courage comes to rescue, but too late, as Muriel is assimilated into the Stitch sisters' quilt, where she is welcomed by the other members. These women are from different periods who the sisters had lured in and trapped into the quilt throughout the millennia once they had forgotten their families, in just the same fashion as Muriel.
Courage surprises and ties the sisters up with yarn and helps Muriel to remember her family by sewing a baby picture of Eustace, and his own fur, into the quilt. And in doing so he relinquishes Muriel and the other Quilt Club members, unravels the quilt and transforms the Stitch sisters into a patch of fabric with their picture embroidered. However, Eustace has allergies and is all out of tissues, so he comes into the living room, scares the other women away, and sneezes right on the sisters, much to their disgust.
- Their name "Stitch" is a slight pun as stitch is a basic sewing technique which binds two ends of a cloth together (or close a gap in the same).
- Along with some iconic antagonists, they also have their own leitmotif, a slow, chamber organ track that plays during more than half the entire episode in a single-paced tune.
- They are voiced by Fran Brill, who is known for performing Zoe on Sesame Street. Coincidentally, John R. Dilworth made a series of animated shorts called Noodles & Nedd for Sesame Street, alongside an animated short called "Felines."
- It has been suspected that the sisters weren't always conjoined twins; it was something to do with the quilt they own that made them the way they are now. Perhaps their bodies were joined in order to increase their lifespan.
- They resemble Mrs. Melisha Tweedy from the Aardman movie Chicken Run.
- They resemble Yubaba and Zeniba from the Studio Ghibli movie Spirited Away. The concept of the characters are also a bit similar.