The One in the Middle Is the Green Kangaroo is a children's book published in 1969, written by Judy Blume and featuring different illustrations over multiple editions.

He is a middle child and feels emotionally squashed between his older brother Mike and his younger sister Ellen.

And Freddy --because Ellen was now the youngest-- he was forced to deal with the fact that he was the middle child.)

Then Ellen cried and told Mrs. Dissel that Freddy pinched her when she messed up, wrecked, and knocked down his blocks.

[2] The book was originally published in 1969 by the Reilly & Lee imprint of the Henry Regnery Company with illustrations by Lois Axeman.