Manny Heffley

Manny Heffley is Greg Heffley's younger brother, who is spoilt rotten. He calls Greg "Bubby" throughout the first book. Greg's illustrations depict Manny having an overbite and his teeth far apart. According to Book 1, Manny is a fan of the television show Sesame Street, especially the C is for Cookie sketch. Manny is isn't at all good at potty training, because of Uncle Joe telling to watch out for the 'Potty Monster', which at one point prevents him from going to the toilet for six months. In the Movie, He is played by twins Connor and Owen Fielding. Manny is loosely based Patrick Kinney, Jeff Kinney's younger brother and there is a chance than his full name could be Manfred. Also, he has cried in all of the books.

Personality
Manny Heffley is far more spoiled than Rodrick and Greg. He is extremely selfish and paranoid, never caring for his brothers at all, and panicking at anything that may harm him in any way. He always gets out of trouble and gets whatever he wants in his life, by showing cute and troubled looks. He is also spoiled to the extreme by his mother, which always makes Greg unhappy.

Greg Heffley
Greg and Manny do not seem to get along very well, mainly due to his mother interrupting in their fun. An example could be in Rodrick Rules, where Manny laughs due to Greg pulling funny faces, then his mother interrupts, telling Manny that he could be 'killed', setting Manny off in tears. Manny always interferes in Greg's sleepovers, often forcing Rowley to leave early. In The Last Straw, Manny starts calling Greg 'Ploopy' instead of Bubby. This was because Manny's blanket got thrown away, setting him off in anger, even though Greg hadn't got anything to do with it. Manny, also complains about the simplest of Mistakes on Greg, even being the nicest ones.

Gramma
Manny has a somewhat unknown but curiously relationship with him and his brother's Grandmother. Their Grandmother mainly have pictures of Manny everywhere. but it was shown that Greg was shown in one of the pictures, but only has the back of his head showing.

Crying
Manny has cried atleast all the time throughout the books. Here are a list of his cries in the books.
 * Diary of a Wimpy Kid: Cries after accidentially swallowing a black thread, believing it was a Spider.
 * Rodrick Rules: Cries after Susan tells Manny "You Could Have Killed Him!"
 * The Last Straw: Cries when Rodrick melts his toys, and cries at Church when Greg calls him a 'Ploopy'.
 * Dog Days: Cries after being told that the Hump is the worst seat in the car.

Trivia

 * Manny apparently hasn't shown to have his birthday yet, but may be shown in Book 5.
 * He stops calling Greg 'Bubby' or 'Ploopy' by the fourth book.