Magenta is Miranda's pet and Blue's next-door neighbor. she is an artistic female puppy who loves to take and draw pictures. Like Blue, she cannot speak, but she can bark to communicate with others, mainly other dogs. She barks similar to Blue, but instead of "Ba Bow Bow", she barks "Ra Row Row".
Magenta looks exactly like Blue, except she's a magenta color with darker spots. As of "Magenta Gets Glasses", she wears purple glasses. In the reboot, she does not wear glasses, and her fur is more defined. She get glasses again later in the series.
She also appeared in "Blue's Big Holiday" where Magenta herself was sliding down a snowy hill on a sled.
And the 3rd letter Magenta appeared in was in "Magenta's Messages" where she was seen at the beach. It was more like an email instead of mailing to someone in person.
Magenta also appeared on the call reminder on the bulletin board in several episodes; including "Blue's Story Time" (her debut episode and the 1st to show the bulletin board, making her the very 1st call reminder character), "Adventures in Art", "Blue Goes to the Beach", "Blue's ABCs" (which also has "Call Magenta." on it), and several others.
Even though she didn't appear in person in "Colors Everywhere!", Magenta was among the friends that were painted on the Portrait of Pals. She was also mentioned in the skidoo segment after Joe and Blue learned that the colors purple and red make the color magenta.
Even though her painted picture shows her with her glasses, Blue had a picture of her without them (which was likely taken before "Magenta Gets Glasses").