Lynn L. "LJ" Loud Jr. is the fifth-oldest of Lincoln Loud's ten sisters on The Loud House, aged at 13 years old in seasons 1 through 4, and 14 years old in season 5. Named after her father, Lynn Jr. is a very energetic, athletic girl who enjoys playing every sport that exists, even making a sport out of everything else she does. She tends to start competitions among her siblings, which tends to cause trouble for everyone because of it (even if winning is not involved).
Lynn strives to be number one in every game that she plays, and typically pulls off unsportsmanlike gloating whenever she wins. Whenever she loses, she throws a tantrum, or makes excuses. Lynn is also quite superstitious, often worrying about bad luck and performing a series of good luck rituals before her games. She is also sometimes not above using underhanded tactics to win, such as distracting Lincoln when he is trying to answer a trivia question. She may be getting over this, however. In the episode "Net Gains", she is drafted onto a terrible basketball team called the Turkey Jerkies and eventually learns good sportsmanship, even congratulating her teammates despite that they ultimately lose the championship.
After Lola, Lori, and Luna, she is the fourth most easily angered Loud sibling and is the most prone to physical confrontations. She also tends to call Lincoln by the nickname "Stinkin'".
Despite her tomboyish attitude, she shows no shame in using puppy eyes to get what she wants, such as bunking in Lincoln's room in "Space Invader". Also, in "Heavy Meddle", she gets as excited as the rest of her sisters after finding out about Lincoln's apparent romantic situation.
Lynn is very superstitious and makes up ridiculous assumptions, because in "Sleuth or Consequences", where she tells Lincoln that she never "bombs the toilet" before a big game of roller derby because it's bad luck. This is also prominent in "Intern for the Worse", where she doesn't allow her teammate, Margo, to use the bathroom, because of the same belief. In "Cover Girls", she tells Lincoln to cover for her while she is at the batting cage to hit baseballs to avoid spring cleaning, and she said if she didn't hit the first ball, she'll have bad luck all throughout the baseball season. This is shown again in "No Such Luck", where she is shown to perform good luck rituals, and unfairly believes Lincoln is bad luck when he comes to her game and she loses, ruining her winning streak.
Lynn is also very immature, as shown in "Cereal Offender" when she rides on carts in the grocery store and wrecks several aisles. Another example of her immaturity is shown in "A Tale of Two Tables", where she participated in the food fight with her siblings. Another part of this immaturity is her poor sportsmanship. When she loses, she starts throwing tantrums, and if she wins, she starts gloating at others, until someone makes her realize she's hurting their feelings.
In "Middle Men", Lynn revealed that she had an extremely miserable life in her first year of middle school during the 6th grade. Back then, she was sweet and sensitive, but after being bullied multiple times, she thought that if she acted tough like everyone else, she would stop getting picked on. Although it worked, it has just caused her to become more aggressive over the years. But she is still caring and didn't want her brother or Clyde to suffer like her.
Episodes focusing on Lynn
- "Space Invader" (main antagonist)
- "The Loudest Yard"
- "No Such Luck" (main antagonist)
- "Lynner Takes All" (main antagonist)
- "Net Gains"
- "Sitting Bull" (main antagonist)
- "Middle Men"
- "Hero Today, Gone Tomorrow"
- "Good Sports"
- "Singled Out"
- "On Thin Ice"
- "Cow Pie Kid"
- "Hurl, Interrupted"
- "Friday Night Fights"
- "Overnight Success"