Around the time that Baby Bear became a regular character, he was paired with Telly Monster, and the two became best friends. Later, his parents, Papa Bear and Mama Bear, were introduced on the show. In 2003, his baby sister Curly Bear was born, turning the Three Bears into four. He likes to eat porridge.
In Season 31, Baby Bear created an imaginary friend, Hero Guy.
Baby Bear speaks with a speech impediment; more specifically, he sometimes pronounces his Rs as Ws. For example, "Super Hero" is pronounced by Baby Bear as "Supo Hewo". (He appears to have the R/W speech impediment, but it is inconsistent, eg, he pronounces his sister's name Curly with the R, as well as Rs in non-stressed syllables and Rs at the end of sentences).
In the 2002 special Elmo's World: Happy Holidays!, it was revealed that Baby Bear's family is Jewish. However, Baby Bear is seen participating happily in the Sesame Street Easter picnic in the 2007 book Rosita's Easter on Sesame Street; he brings Easter Braided Bread to the party. His birthday is May 12th.
In season 36 and 37, he was seen attending Storybook Community School.
In a 2009 episode, he inadvertently helps Abby Cadabby find one of her missing freckles when his mother holds up Baby Bear's underpants, much to his embarrassment. (This is strange, since Baby Bear doesn't wear pants).