Being the oldest of the siblings, Lori is bossy, condescending, and has the second nastiest temper after Lola. But aside from that, she is also cute, friendly, insecure and protective. As the oldest sibling, she is supposed to act responsibly and maturely, but she doesn't always act like that, and instead, she behaves like her youngest sisters, like in "Left in the Dark", where she's afraid to go down into the dark basement.
She likes to keep her shoes under the bed for unknown reasons. She doesn't like the others touching her possessions, especially her cell phone, which seems to be her most valuable object. The reason for this is that she doesn't want to waste her phone memory for messages other than the ones from Bobby. She's also very territorial as she loudly yells at anyone who goes into to her room without permission before kicking them out.
In some occasions she acts without thinking, and commits malicious actions against the others for her own selfish benefits, like in "Driving Miss Hazy", but since her love for her family always comes before any petty problem, she has a caring heart underneath a rough exterior, and she will always try to fix her mistakes. Deep down, Lori is insecure and is usually frustrated with the responsibilities and burdens of having to take care of her nine wild sisters and only brother. It is also shown that while she gets annoyed and easily agitated by a lot of people, she feels lonely without the people she loves and cares about (such as Bobby and her family) and her worst fear is in fact, losing them forever.
"Lori Loud is 'literally' the oldest of the Loud children. She's the self-proclaimed boss and the only sister with a driver's license...so it pays to stay on her good side. A professional texter and avid eye-roller, Lori is never afraid to tell people how she feels."
Lori is the tallest sibling of all. She has large blonde hair (a genetic trait she shares with her mother, even though her hair is longer). Her original design depicted her with pink eyeshadow, a white tank top, navy blue shorts, and black shoes. Later it was changed with a light blue tank top, brown cargo shorts, blue slip-on shoes, and blue eyeshadow. She also wears white pearl earrings.
Her nightwear includes a sky blue nightshirt and blue slippers, but later, her current one contains a white tank top, and small blue and white shorts, with a square pattern, as seen in "Space Invader" and "Overnight Success". Her swimsuit is a two-piece light blue bikini.
In "Come Sale Away", it's revealed that she used to wear braces, a blue ribbon, and previously suffered from acne when she was younger. In "Anti-Social", it also shows she used to wear glasses.
Her phone is a handheld object owned by her. She often talks to her boyfriend Bobby with it, but she also talks to other people from time to time, and text with it as well. A common animation goof with her phone is that it changes colors at times.
In the alternate universe where Lincoln has ten brothers instead of ten sisters, Lori is a boy named Loki Loud. Unlike Lori, Loki is even more selfish, greedy, and very bossy around the others. He is also mean and abrasive towards Lincoln and mocks him for Luke (Luna) using him to clean the toilet, Leon (Lily) for biting his thumb when he gets a "booboo", and teases him about Ronnie Anne.
However, in the dimension where the sexes of the Loud kids are the exact opposite (meaning that it's one girl and ten boys), Loki's shown to be very caring and protective of his sister, Linka - in fact, Loki's the first of the brothers to ask Linka (technically Lincoln in Linka's body) if she's okay after he and the rest of the brothers heard her screaming in the middle of the night.
Loki eventually turns out to be a product of Lincoln's imagination as the whole adventure was revealed to be a dream, which Lincoln wakes up from it at the end of the episode.
The High Card
In the minicomic Deuces Wild! and its animated adaptation, Lori takes on the superheroine identity The High Card. She is one of Ace Savvy's sidekicks. Her powers are not shown, as she's only seen driving a van. In the comic, she is summoned by Savvy alongside the rest of Savvy's deck to help him and One-Eyed Jack defeat the gas monster. After they defeat it, they prepare to fight against a garbage monster.
In "Pulp Friction", she is only seen driving the van, and her abilities aren't shown.
Lori's pajamas are similar to what she wears in her prototype design.
Her middle name is also Marie, confirmed by Leni in Selfie Improvement, despite Lori's name has an "L" in the middle of her driver's license.
According to Bobby in "Back in Black", Lori is on the varsity golf team, implying she is an excellent golfer. She also talks about attending a golf tournament in "No Such Luck". In "Change of Heart", she is seen going to a golf tournament.
In Lynn's episode of the Listen Out Loud podcast, Lori says that one of the reasons she likes golf is because of her dislike of running.
Lori is the third most feminine Loud sister, after Leni and Lola. She usually wears shorts instead of a dress, but she loves fashion and other stereotypical teenage girl things.
Her mannerism resembles close to Pacifica Northwest from Gravity Falls, since both of them are blonde and sometimes use slang.
From the picture of her feeding baby Lincoln ice cream in "The Whole Picture", it looks like she's worn similar clothes for most of her life.
According to episode 20 of the Nick Animation podcast, Lori's favorite movie is Dirty Dancing.
Her Polish name is Hanna (Hannah) with the nickname "Hania."