Star Butterfly and Marco Diaz deconstruct the typical friends to lovers, Everyone Can See It dynamic. The two are extremely close and comfortable with one another, but while they develop feelings for each other, it takes them both a while to realize it since they're still emotionally immature teenagers. What's more, these revelations come about while the other is in a relationship, with people they have genuine chemistry with that came about since they're under the impression that they were Just Friends. Rather than one of them confessing and triggering a Relationship Upgrade, in both cases they only admit it under duress and it makes things more awkward between the two of them, and puts a strain on their relationship with their respective partner. In short, such a dynamic is unlikely to be neat, tidy and causes a lot of heartbreak for everyone involved.
The Butterfly Family is a deconstruction of The High Queen. The Butterfly queens were originally depicted as benevolent heroes who saved their people from extinction by eradicating the barbaric monsters with their magic. But as the series progressed, some of the Queens' actions became more and more villainous and xenophobic, casting the queens in a morally dubious light. Reconstruction with other queens who genuinely wereThe High Queen such as Comet.
It's deconstructed further by the revelation that the next heir to the throne was switched out with a peasant hundreds of years ago and in a later episode, reveals that the first queen was a peasant as well. There is no blood difference between royalty and the peasantry and there's nothing particularly special about the royal family that makes them worthy of ruling. Nonetheless, the system is maintained only because the people want a Mewman on the throne who will keep the xenophobic status quo rather than a Half-Mewman Hybrid.
Meteora Butterfly is a deconstruction of the Lost Orphaned Royalty. Her backstory sounds like it could have come from a fairy tale or Disney movie: a lost princess who had her throne stolen from her and was raised by an abusive guardian, who later finds out who she really is...but by the time she learns the truth, she's a bitter old woman, not a young girl who still has innocence in her heart and the potential to grow. Once upon a time, she was a sweet little girl, but being raised by an emotionally abusive robot caused her to grow into not a brave and kind heroine, but a deeply emotionally damaged person who cannot understand love and only understands how to inflict suffering. Her trying to take back her rightful throne is not a triumphant Rightful King Returns moment, but a destructive Suicidal Cosmic Temper Tantrum where she rampages across Mewni while sucking out the souls of innocent people, eventually having to be stopped by her mother Eclipsa who loves her but can't let her keep destroying the kingdom.
The Monsters are a deconstruction of Always Chaotic Evil. They were initially depicted as nonhuman barbarians who lived for violence and death, opposed by the benevolent and orderly Butterfly queens. It was eventually discovered that the monsters only acted the way they did because first the Mewmans forcibly took their land, then cruelly oppressed/killed them, then sanitized their own actions to make themselves look good. In reality, the monsters either fought in self-defense, retaliation or for outright revenge for what the Mewmans have done to them.
Glossaryk deconstructs Omniscient Morality License, Troll and Trickster Mentor. While he is a borderline all-knowing being with extensive knowledge of magic, he rarely shows concern for the physical or emotional well-being of others to the point that even his own allies have a hard time tolerating him. What's more his apathy towards morality means that when Ludo captures him he has no problems teaching him, making the villain a much greater threat, and does nothing to stop Toffee's plans despite being in a prime position to do so, which lead to a Near-Villain Victory. His teaching methods also vary wildly in their effectiveness, since it's hard to tell when he's being serious or just messing with his students to Moon, Star and Ludo's frustration. At the very least, he appears to be completely sincere when teaching Meteora. As well, the second he pulls his usual tricks on someone (Ludo) not inclined to tolerate it and unstable and impulsive enough to retaliate, he winds up dead after pushing Ludo too far.
