In Rodrick's online and book appearance, his head is completely round except for the part around his eyes. It is just like Greg's; it has no line and five hairs sticking up on his head. He is always seen with a frown on his face (unless he is harassing Greg), and one ear. His eyebrows appear to be thick and bushy, colored only black. Normally, eyebrows only appear on characters which are angry, which makes it hard to know if he is angry or not. However, his eyebrows also appear when he was a baby. Rodrick also has a tattoo with the name of his band as shown in the film and in The Last Straw (However, it was blurred in the film by water, showing that it must removable or Henna).
In the movie, Rodrick's appearance has vastly changed. His skin now appears as a golden tan, with hazel eyes and dark brown hair.
Like Greg, it is explained that he is only good at a few things, namely everything, and spends most of his time on it, which deters him away from schoolwork. He would much rather sleep over doing anything else. Fitting with his love for music, Rodrick is the lead drummer of a group called Löded Diper, a metal band. Its lead singer is a man whom Rodrick's parents are afraid he will become: Bill Walter, a 35-year-old high school drop out who is unemployed and still lives with his parents.
Rodrick is extremely lazy and underactive when it comes to school, which explains where Greg gets his laziness from. Greg believes that Rodrick is lazy and unintelligent in all other areas, though there are clues that show otherwise. Rodrick clearly isn't the smartest of his family, since he hardly makes an effort at school and constantly asks his parents to do his work for him. Although Rodrick is portrayed in this manner, he is actually quite manipulative and intelligent in manipulating other people.
Rodrick is said by Greg to be a terrible speller (though he spelled everything right besides band names on his activity page in the Do-It-Yourself Book) and is said to be completely ignorant about how to use any electronic device (although this may be more manipulation to get things done for him; he is clearly seen using a music player in Rodrick Rules and a cell phone in a flashback in Dog Days, and in The Ugly Truth it is shown that he uploads photos online and he is again seen using a music player once again in Hard Luck). Rodrick did terribly back in elementary and middle school.
The only reason Rodrick is doing slightly better at high school is because he cheats by having his dad do all the work for him, but in Hard Luck, it is said his first quarter didn't go well, meaning that his father might have stopped helping him. He is shown to misspell a lot of words even in the recent books and has less knowledge of things than Greg, for example thinking a lock is a microwave and also thinking bacon is taken from pigs like eggs from chickens.
- Rodrick's science project and his grades for his SAT exams have not yet been revealed so far, though there is a possibility it may come in future books. In the online version, however, Rodrick got no ribbons for his science project, though this may be subjected to change.
- Rodrick once slept for 36 hours.
- Rodrick's room is located in the basement of the house. In the film however, his room was in the attic.
- Most of the characters in the book only show their eyebrows when they are mad. Fitting with Rodrick's antagonistic behavior, however, he always looks angry due to him having eyebrows all the time.
- It's hinted in the online book that Rodrick has never had a legitimate girlfriend, since Greg has never seen him with a girl. However in the Do-It-Yourself Book, it is hinted in a letter that he was associated with a girl named Lindsey, who seemed to break his heart in some way, shape or form. This may explain why he acts incredibly rude and immature.
- Rodrick is a major antagonist of the three series; book, film, and online version. However, he isn't an antagonist in The Third Wheel or Hard Luck.
- In The Third Wheel, he is mentioned only a few times and is a background character; he doesn't bother or prank Greg at all (except for flashbacks), same in Hard Luck.
- He has had a minor role in the recent books, since Dog Days, with the exception of The Long Haul.
- In the online version, he has a pick-up truck and the van belongs to Bill Walter, however in the book and film the van belongs to him.
- He is thought to have a love for pranks. In Diary of a Wimpy Kid: Rodrick Rules (the movie) he takes Greg to a mall and throws fake vomit on cars. This ends with the boys being chased through a dumpster and the mall by an angry gym teacher (Coach Malone) . He is also shown pulling pranks on Greg, other adults and teenagers in many of the books, for example putting fake vomit on cars, shooting spitballs on a man and mentioned to have pranked people with dollar bills under the boardwalk
- Its most likely he has a social network account because according to Greg he uploads pictures of his band and embarrassing ones of Greg on a site.
- Rodrick has several times manipulated other characters do things
- Despite appearing on all the books first page (which generally has all the protagonist of the book) Rodrick is only a major character in the second book and the ninth book with every other appearance being a minor (under 30 pages)
- Rodrick is show to be taken advantage of for the first time in the 10th book. This is also the first time he doesn't squeeze out of a situation from Dad.
- If Greg takes his stuff that he is using, He usually gets mad.
- Rodrick cut off some of his hair and one of his eyebrows in the online version when he grew a groaty mustache.
- In Dog Days, Rodrick got Sweetie's name wrong on the water bowl, which he spelled Sweaty.
- Rodrick is usually the main antagonist in Diary of a Wimpy Kid, minor antagonist and anti-hero in Diary of a wimpy kid: Rodrick Rules and Diary of a Wimpy Kid: Dog Days