Lisa Loud/Relationships

Her siblings generally
She often looks and talks down to her siblings due to her prodigy intelligence. She likes to use them as test subjects for her experiments much to their fear. She loves her family but otherwise is all think and no feel, even against the gothic Lucy, because of this, she doesn't seem to have much of a connection with anyone, but is always available to help them with any problem.

Lincoln
Lincoln doesn't have a lot of interactions with her, however he's afraid of her being angry, because he ruined something.

In "Butterfly Effect", Lincoln breaks Lisa's chemical bottles with his yoyo and he fearfully believes Lisa will get mad for what he did, but instead of being angry she becomes ecstatic with him and thanks him for proving her hypothesis and for admitting what he did.

In "Heavy Meddle", she easily finds out about Lincoln's secret that he's being picked on at school. She states that she does not have enough room in her brain for keeping it to herself and tells it to Lynn, who in turn tells the other sisters, much to his chagrin. Though this is likely out of concern for the well-being of their only brother.

Lincoln is very disgusted when Lisa uses her family as lab rats and performs experiments on them without their knowledge. He angrily yelled at her when she experimented on Leni in "Project Loud House" and Lily in "Changing the Baby".

Lori
Lisa and Lori don't have a lot of interaction, although Lori already knows about Lisa's strange experiments. She hates Lisa's poop study as shown in "Undie Pressure", and doesn't like that she uses her siblings as "guinea pigs" as shown in "Left in the Dark". In "Driving Miss Hazy", Lisa does Lori's math homework in exchange for driving her to the planetarium.

Leni
The relationship that Lisa has with Leni is like Dexter and Dee Dee's relationship from Dexter's Laboratory. When Lisa creates a new invention, Leni is the first person whom she tests it on, and this could be because of Leni's poor intelligence. This is evidenced in various episodes like in "Project Loud House" when Lisa changed Leni's blemish cream for an experimental skin pigmentation ointment, turning her skin blue.

In "Butterfly Effect", Leni becomes smarter than Lisa after being hit in the head with a coat rack. This caused Lisa to give up on science, and gets a job on a gas station.

Given their complete opposite IQ levels, Leni's doltishness tends to get on Lisa's nerves at times.

Luna
Lisa and Luna don't have a lot of interaction between them. However in "The Sweet Spot", is revealed that Luna's singing annoys Lisa because it gives her tinnitus. Also in "For Bros About to Rock" is revealed that Luna ruined her first opera by jumping off the stage and landing on the orchestra, in an attempt to stage dive. Lisa also refused to provide Luna shelter in "April Fools Rules", stating that Luna should have more prepared.

Luan
She and Lisa don't have too much interaction. Like all her siblings she gets annoyed by Luan's unfunny jokes. In "Left in the Dark", Lisa uses her to prove her "Gloweos" cookie, resulting in Luan's entire body glowing.

Lynn
She and Lisa don't have too much interaction. In "Butterfly Effect", it is revealed that Lisa tutors Lynn for her exams to let her stay in her sport teams.

In "In Tents Debate", they both want to go to Dairyland for their family vacation and try to get Lincoln to vote for their side.

In "Heavy Meddle", when Lisa couldn't store Lincoln's secret that he was being picked on at school in her brain, she told Lynn who told everyone else and claimed Lynn's brain had plenty of room. Lynn thought it was a compliment at first, but then realized what her genius sister meant.

Lucy
They don't have much interactions but they argue about their science and magic. Lisa questions scientific possibility of Lucy's fortune telling in "Raw Deal". However they can cooperate if necessary as seen in "Come Sale Away".

Lily
Lisa has a good friendship with her, as both of them have to share a room. In "Changing the Baby", Lisa tries to use Lily on an experiment that appears to be very dangerous. She also tries to implement her interests on Lily because she has no one else whom shares the same interests as her.