Rosie Tollar, is Caillou's adorable and very beautiful 8 year old little sister. In the French novels by Christine L'Heureux that the show is based on, her name is Moussline. She is also the daughter of Boris and Doris.
In Caillou, Rosie tended to cry over almost anything (usually resulting in her needing to be comforted by either parent), yet she can giggle at anything she sees as funny (both normal behaviors for kids her age). Calliou usually showed love to Rosie (despite some quarrels between the two). In the Caillou episodes "Halloween" and "Caillou's a Clown", she was scared of clowns, but he was able to convince her to not be afraid of them. She couldn't talk as well Caillou can (usually just short sentences (some even being one word or a sound effect) plus speaking in the third person most of the time). It is shown in "Olive Muddle" that Rosie likes olives. Rosie's favourite song is "Ring Around the Rosie." Rosie does not like beans, as shown in the episode "Caillou becomes a waiter". She's developed a lot in the later seasons. In "Caillou Helps Out" Rosie starts teething, and in "Am I Big Yet?" She went through a growth spout. In School Daze, Rosie has changed a lot. She now cries less often than she did when she was 2. She is able to speak fluently. She would often bother Caillou whenever he was using the computer. Rosie is shown to love animals a lot. In “Triple Birthday Party”, She is seen cuddling with Rigby throughout the whole episode. She is shown to find Brian very adorable in “What you Read is What you Get”. But other than that, she thinks Gilbert is the cutest animal of them all.
Rosie has tan skin and brown eyes. In the show Caillou, she had orange hair, but prior to the School Daze series, her hair was dyed blonde.
In Caillou, Rosie had short orange hair and wore a blue long-sleeved calf-length dress with a light blue collar and a white/yellow sash, red ankle-length socks, and blue Mary Jane shoes.
When she was a baby, her hair was shorter, and she wore a yellow and red onesie.
School Daze(Seasons 22-37)
In Seasons 22-37 of the School Daze series, Rosie got a new look. Her hair was dyed blonde. Her new outfit consists of a frilly white T-shirt with a turquoise butterfly on it, a light orange bracelet on her right wrist, pink pants with turquoise pockets, and orange sneakers.
During the Summer Era, Virtual Paradise, and Season 1 of Advanced Education, she wore a pink hat with a purple band around it, which has a yellow flower attached to it, a long, pink coat with purple buttons, a white short-sleeved under-dress(turquoise in Virtual Paradise and Advanced Education), a white and yellow scarf, a silver necklace, white socks, and purple shoes. She switches back to her main outfit in Endless Summer.
In Season 2 and the rest of Advanced Education, Rosie wears a new outfit, which is a combination of her 2 main outfits. Her hair is shorter, and in a similar style to her hairstyle from the Caillou series. Her new outfit consists of a frilly pink t-shirt with white pinstripes underneath a sleeveless variation of her original blue dress from the Caillou series, which has a light blue collar and yellow sash. She also wears white leggings with a turquoise butterfly pattern on them, the same orange bracelet from School Daze, and her red socks and blue Mary-Janes from the Caillou series.
In the Dog Daze of Summer series, Rosie’s outfit has the same exact color scheme as her original School Daze outfit. She wears a white sleeveless dress with pink trim. The dress has a turquoise butterfly pattern on it, similar to the design of her shirt from School Daze Seasons 22-37 and her leggings from Advanced Education. She also wears pink sandals with turquoise straps, and her orange bracelet is worn on her left wrist for a change.
In the Senior Year series, Rosie's hair grows longer and she wears an off-white and pink striped t-shirt underneath a pair of short blue overalls with gold buttons and light blue cuffs, pink and white sneakers without socks, and a turquoise butterfly-shaped hairclip. Also, her orange bracelet switches back to her right wrist.
In cold weather, she wears a green jacket with yellow trim and a red hood over her pink shirt and blue dress, red mittens, and dark green boots with red on the top.
During the Ring Ceremony, Thanksgiving at Gammy's, and the Best Buddies Prom, Rosie wore a sleeveless blue dress with a pink scarf, as well as brown sandals with pink straps.