Luan Loud/Relationships

Her siblings generally
Luan tells a lot of jokes, but never make any of her siblings laugh. She also plays a lot of practical jokes on them, some of which seems truly mean spirited, like the bucket of water over the door prank on Lincoln in "Project Loud House", which would have ruined his homework project he worked so hard on. In other cases, the impression does comes off that she doesn't mean for anybody's feelings to be hurt.

She's always willing to help them when they have a problem and she does have a generally friendly personality outside of her pranking nature, but can get violent tempered with her siblings, as seen in "The Sweet Spot".

In addition, it is shown in "April Fools Rules" that on April Fools Day she becomes immorally crazy and completely merciless setting pranks everywhere in the house, giving all of her family unhealthy fear of her, even Lola, and their parents, unable to control her. This was to the point Lisa built her own shelter away from her and the others locked themselves in Lincoln's room and nailed it shut with Mahogany boards.

Lincoln
She can at times pull nasty pranks on him but this is likely due to the fact that she is trying to be funny, and isn't really aware that what she did can cause him grief, so it appears that she does it without malicious intentions.

In "Making the Case", he came to her for advice on making funny viral videos, and she happily gave him the idea to always have the camera on. After he humiliated all his sisters Luan was the only one who had any desire to speak with him. She gave him advice on how to fix his relationship with his sisters. When he thought he was going to be expelled from his family in "Ties That Bind", he left her his comic book collection, but she refused them as she didn't want him to leave.

In "Funny Business", Luan makes Lincoln her clown assistant, but Lincoln accidentally gets laughs from the kids and loves it so much, that he starts to take away the attention using pratfalls. The two have a falling out, but eventually make up, and become closer siblings from the experience.

Leni
She and Luan have a good relationship and they can be seen having fun in some episodes. In "Linc or Swim", Leni doesn't know the rules of the game "Marco Polo", much to Luan's annoyance and/or dismay. Because Leni is afraid of spiders, Luan scares her with her plastic spider for fun like in "No Guts, No Glori" and "Along Came a Sister".

Luna
Because Luan has to share a room with Luna, they look to be on good terms. Sometimes Luna helps her being the "band show" or bringing mood music every time Luan is practicing her stand-up comedy puns.

Lily
Luan and Lily have a good relationship. Luan likes making Lily laugh and feel happy. In "Changing the Baby", she tries to implement her interests on Lily because she had nobody that share her likes. In "Homespun", she able to translate Lily's baby language.