- "Their school might be tough, but we got strategy on our side!"
- ―Victor Clay
River Rock Rivalry is the sixth comic in Season 1 of Sibling Rivalries: The Next Chapter, and the 51st comic overall.
Green Bay Southwest High School faces against their rival school, Green Bay Notre Dame Academy, to win the Lake Fox Rock back. Adrian, Aaron, Victor, and Anthony go to the varsity game on Friday night to watch their school play, while Packie and his family are unable to make it as they are at a family reunion. Adrian and the guys, however, end up unknowingly coming to the game an hour before it even starts, and this causes an argument with one another.
♥ = character's debut
♠ = character does not speak throughout comic
♣ = character is mentioned only
♦ = character appears in a speaking/non-speaking cameo only
- Patrick McReary
- Francis McReary
- Gerald McReary
- Derrick McReary ♠
- Kate McReary ♠
- Maureen McReary-Wilson ♦
- Hector Wilson ♦
High School GroupEdit
- Angel Chacon
- Salvador Real
- Eduardo Tena
- Claude Tena
- Louis Wilson ♦
- Carol Wilson ♦
- Troy Wilson ♦
- Tony Gonzales ♦
- Salvador Martinez ♦
- Bruce Warren ♦
- Isaiah Trevino ♦
- Miguel Ibanda ♦
- Joseph Levine ♦
- Travis Ingram ♦
- Cameron O'Neill ♦
- Ethan O'Neill ♦
- Chloe O'Neill ♦
- Dillon O'Neill
- Aaron O'Neill
- Robert O'Neill
- Gertrude Conner ♦
- Nicholas Conner ♦
- Lauren Conner ♦
- Amy Conner ♦
- Rachel O'Neill ♦
- Paul O'Neill ♦
- Green Bay Southwest High School
- Trojan Cafe
- Football Field
- Wilson Residence
- Living Room
- Ethan and Chloe O'Neill's House
- Living Room
- This comic was released exactly three years after "Patrick McReary: School President" and two years after "Wouldn't It Be Nice?". This is also the third comic in the franchise to be released on September 8.
- In addition, this comic was also released exactly ten years after the premiere of iCarly, which was occasinally mentioned in the original series as one of the McReary siblings' favorite shows, even after its conclusion.
- Green Bay Southwest High School and Green Bay Notre Dame Academy are, in fact, rivals in real life as well.
- An alternate plot for this comic was the freshman football team would have to train for their big game against Green Bay Notre Dame Academy, but was scrapped as the varsity team would really be the team to settle the rivalry. The game between the freshman team is briefly shown in this comic though it followed a different plot line.
- The original title for this comic while following that plot was "Unfriendly Rivalry".
- This is the first TNC comic to focus on somebody else other than Packie, as Adrian and the gang are the main characters of the main plot, with Packie only having a minor role in the brief sub-plot. This is also the ninth time total that Packie is not the main focus of the comic. ("The Curse of the Milderbeast", "Roommates", "The Ballad of Anti-Cutecumber", "Love is What Makes the World Go 'Round", "A Day With Drew Brees", "The Pool Date", "The Return of Armando Vasquez", "Trading Places")
- This is the fourth comic to feature a football game, after the original series comics "The Big Trade-Off", "The Football Faker", and "Trading Places".
- Maureen's side of the family returns after they all made a cameo appearance in "ApRiL fOoLs DaY: wIsCoNsIn StYlE!". This is also the third appearance of Cameron O'Neill and Ethan O'Neill's family after "Uncle Cameron Moves In" and the aforementioned comic. This is also the second appearance of Ethan and Chloe's house after "Uncle Cameron Moves In", where the living room is now shown.
- Victor acts out of character when he is upset after the freshman team lose their game against Green Bay Notre Dame Academy's freshman team, as usually he is always optimistic.
- Bruce Warren makes his second appearance.
- This is the first time that the Wilson Residence (Adrian and Troy's house) has appeared since "The Step-Cousins Wilson" in Season 4 of the original series (also the debut of these characters).
- For more detail, the football players are now shown to have their hair pushed down after wearing their helments.
- Starting with this comic, Anthony is seen wearing braces.
- As this comic takes place before "The Homework Night Redirection" which is set after every other Season 1 comic, Gerry does not know who Victor is in this comic, while the two meet each other in that comic.
- This is Salvador and Eduardo's first speaking role since "The Golden Boy".
- Similar to "Yearning to be Young", the final scene of this comic is set in the future (in this case, September 13, 2019, where another game between Green Bay Southwest and Green Bay Notre Dame Academy is taking place). The Trojans are shown to lose the rock in 2019 after holding onto it since 2016. Adrian and the boys (now 18 years old and seniors) are on the varsity football team, along with Gerry (now 16 years old and a junior) who is also on the team.
- This shows that Adrian and the guys will continue to play football throughout all four years of high school.
- In addition to having the final scene of the comic mirror that of "Yearning to be Young", the other McReary siblings appear with rougly the same outfits that they wore as adults in the epilogue of that comic, which is set in 2033 rather than 2019.
- Similar to "Love At First Plight", Packie only has one scene with Adrian and the others in the beginning of the comic, then Packie does not appear with the other four for the rest of the comic as the plot splits.