Ruthie is the only adult Esperanza knows who still likes to play like a child. Ruthie is the daughter of Edna, a mean woman who owns the apartment building next to Esperanza’s house. Esperanza first met her when Angel Vargas was teaching the girls to whistle, and Ruthie suddenly appeared, whistling beautifully. Ruthie acts anxious when she goes shopping with the children, but she likes candy, and she “sees lovely things everywhere,” like shapes in the clouds.
Ruthie shows the childlike love of beautiful things that Esperanza and her friends have demonstrated before (which for them is a way of escaping, and improving their lives), but Ruthie is an adult, so her childishness is just another way of keeping her trapped. It is unclear when this anecdote takes place, as Angel Vargas, who fell and died, is still alive.
One night some of Edna’s friends invite Ruthie to go out and play bingo, but Ruthie is anxious and paralyzed by the idea of leaving with them. Esperanza says that Ruthie is good at many things, but instead of getting a job she got married when she was young. Esperanza can’t understand why Ruthie returned to live on Mango Street with her mother, but Ruthie says she is just waiting for her husband to come and take her away. But he never comes.
It is never explained whether Ruthie’s stories about her own past are true or made up, but it’s clear that she is another trapped woman of Mango Street, her potential squandered. Ruthie shares some of Esperanza’s talents and creative spirit, but she lacks the strength to try to escape. Instead, her escape seems to be a kind of regression back into childhood. It's also suggested—but never confirmed—that Ruthie's childishness may come from some kind of intellectual disability or mental illness.
Ruthie loves books, but she can’t read anymore because she gets headaches. She says she used to write children’s books. Esperanza brings library books to Ruthie, and once she memorizes the poem “The Walrus and the Carpenter” (from Lewis Carroll’s Through the Looking Glass) and recites it to Ruthie. Ruthie is clearly moved by the beauty of the poem, but all she can say is that Esperanza has beautiful teeth.
Esperanza is perhaps looking for more encouragement in her writing (as Aunt Lupe gave her), but Ruthie is unable to express herself properly after hearing the poem. This is another example of the power of language – Ruthie has poetic potential, but she cannot use it and so remains stuck, while Esperanza continues to grow.