Firstly is the title character in the story "Prince Firstly's Little Surprise," as told by Mommy Snuffleupagus to Snuffy and Alice. The prince must adjust to being a big brother to Princess Azalea, and to all the attention shown to the new baby.
He gets envious and pulls a few pranks for attention, but all this does is make Lord Elmo annoyed with him. Coming to the conclusion that nobody wants him around, he runs away, but his mother Queen Quinella makes it clear to him that his parents still love him all the same. Firstly learns that it feels nice to have a younger sibling who looks up to him, and he grows to love her.