Nick Mallory is deliberately screwing with TrinaSeriously, he is nice to pretty much everyone but her, and seemingly takes a chance to insult and degrade her whenever he feels it's apropriate ("Nick Mallory doesn't dig abominations", Nick Mallory knows someone who could use a mint... you!"), so it's probable he is simply leading her on to cause her misery. Which, depending on who you ask, it's either karma, or him being a bigger asshole than her.
In the final episode...Trina will discover the band has been using her diary, some epic battle against her will occur and she and Corey will reconcile as siblings. The band puts on a huge concert, Corey manages to write lyrics all on his own, and Laney confesses her love to Corey and they become an official couple.
Trina wants to destroy Grojband because...She had her own band which broke up and left her with no friends other than Mina. She knows how much Corey's friends mean to him and is afraid he will make the same mistakes she did.
Trina will sing onceShe'll go beyond diary and end up singing her feelings.
Trina will get a heart attack some day.Corey will push her too far, resulting in her ending up in the hospital. That will lead to Corey hiring an actual lyricist for his sister's health.
Corey and Trina are the spawns of Satan.If Trina can warp reality when she gets emotional, who knows if Corey has the same ability!
There will be a Romeo and Juliet like situation...Either Kin and Kim or Kon and Konnie will fall for each other and theyre respective bands will be against it.
Corey and Trina is related to Courtney.Courtney and Trina both have the obsession to be the best.
The reason Corey treats Laney like One Of The Guys...Is because he's subconsciously denying his own feelings for her because he's worried that things would get awkward between them.
"All You Need is Cake" was intended as a partial Shout-OutCall me crazy, but this is the second time this troper has seen the desire for a giant cake get in the way of the relationship between an Only Sane Woman who's clearly crazy for a boy that's Oblivious to Love on Cartoon Network. ...MAN, I miss them.
This interesting piece of information gives us an idea for Corey and Trina's pasts.Corey and Trina originally came from different families. Corey's biological parents loved him very much, but Trina was constantly abused by her biological parents. She ended up in an orphanage because of that abuse. Corey, however, witnessed his parents die when he was very young, traumatizing him. Without any other relatives, he was sent to that same orphanage. Eventually, they were adopted by an unmarried man. But the two still remember their parents. They were both the children of musicians. Corey was drawn to music because of his loving parents, but Trina grew to hate rock music because they reminded her of her abusive parents.
Laney is Violet Parr's cousin.Remember when it appeared she was literally on fire? That wasn't a cartoon gag. It was her power as a Super.
The Riffins and Beffs are half-siblingsThis could explain why Corey and Carrie look so alike.
The talking plant from "One Plant Band" is actually Audrey II 2.0.He became Genre Savvy and decided that making humans inhale toxic plant chemicals before eating them was easier.
Corey is from rocklympusHe secretly has the power of the gods of rocklympus which explains some of his abilities (like in the ping pong game)
One of Laney's ancestors was a Disney Princess.She's beautiful, gentle towards all animals, and has a pleasant singing voice.
Grojband is set in the same universe as Scott Pilgrim.Let's see... The series was made in Canada, the art style has some similarities. Other similarities: The Power of Rock. People having weird superpowers, or things resembling superpowers (with Trina altering the environment around her when she goes diary). The overall craziness of the whole show. Sounds showing up in written form on-screen. Heck, being self-aware was also something from Scott Pilgrim. The reason the video game elements from Scott Pilgrim haven't shown up yet is that Grojband is too young for them to manifest, while Trina is probably somewhere near the age when it really starts. Eh, this is WMG, so why not. Plus, Trina has the profile to be a future evil ex.
Trina secretly has Multiple Personality Disorder, but Katrina was the original personality.Corey said no one has called his sister "Katrina" in years, while Katrina herself said Trina locked her up. Maybe Katrina (and the other personalities) originally locked up Trina because she was too dangerous. But one day, something happened that made Trina strong enough to overpower the other personalities and take Katrina's place as the dominant personality.