Yeah, in fanon, I think we all agree when Louis looks especially fashionable, it’s because Lestat dressed him! Louis looks damn fine in torn jeans and a distressed sweater tho, tbh.

And yes, book!IWTV mentioned briefly that Louis had preferred black:

“… and it was [Claudia’s] pleading that forced me to give up my rusty black for dandy jackets and silk ties and soft gray coats and gloves and black capes. Lestat thought the best color at all times for vampires was black, possibly the only aesthetic principle he steadfastly maintained, but he wasn’t opposed to anything which smacked of style and excess.” – Interview with the Vampire

In movie!IWTV, he was already depressed enough, if he was also dressing like someone in mourning, I think it might have been harder to convince the audience why Lestat liked him at all! 

Plus, his wardrobe shows a progression of his character throughout the course of the story. 

• mortal Louis: wears alot of white, he still has his innocence and ability to achieve goodness in the eyes of god or whatever.
• newborn vampire Louis: is sorta uncoordinated, and awkward about killing, and still trying to be the plantation owner, clearly letting Lestat dress him for outings only.
• vampire dad Louis: is more comfortable with killing, and trying to set a good example for vampire daughter Claudia, and at this point is probably letting Lestat buy all his clothes.
• vampire accomplice Louis: is in Paris and trying to fit in there, and at this point is probably letting Claudia buy all his clothes.
• bereaved –> modern day Louis: just picks things that he’ll blend into a crowd with (that casual linen suit he wears to go to the movies).
• Louis talking with Daniel: has dressed up in severe black and white because the interview is meant to be a message to Lestat, and Louis knows Daniel will report what he’s wearing.

BONUS: Louis still has the coat that he wore when he was with Claudia in Paris:

Can you imagine how painful it would have been, returning to the hotel room he shared with Claudia, and all her clothes and accessories exactly as they were when she left it last? ;A;