Grey and Ku are your common enemy and hero couple duo, only Ku isn't all that morally evil hence why they are more rivals, though Ku are manipulating the corrupted souls of those tainted by magic, depending on perspective, Ku can be considered a savior but of course that's about the same as calling a drug dealer your savior because they gave you something that is only temporarily satisfactory but harmful to you in the long run. Notably however Ku has saved Grey and their friends multiple times despite being the one to tell Grey that not everyone lives forever and if you make friends with those weaker than you you're bound to lose them. But really, Ku is a hypocrite of you see the amount of people they save on a daily basis.

Grey's View: they can be a pain in the ass, whatever they do I have to clean up their mess, they had tried many times to get rid of the planet earth just so Papiliosidus can be the only planet in the north solar system. While Ku did say they hate humans for existing, they actually do take care of innocent children and animals. They think that they don't know that they have this soft spot.

Ku's View: they get why they are so admanment on protecting humans but what's the point really? They will all die eventually, even worse, their magic can only come to a fraction of what a Papilio can do, how are they meant to survive? Sure that one human cheated and can cancel magic, but magic cannot be oppressed, they don't get why they are wasting time on this tiny planet when there are bigger fish to fry. Grey said to stay on Earth despite their shenanigans, does that mean they care about Ku?

They first met when Grey and their siblings found a place for the remnants of dragons to stay, the amount of magic in one place attracted Ku to the very dreaded planet that killed their cousin, Wakana, they were surprised to see surviving Papilios, even worse they are part of the royal family, the reason why Papiliosidus was destroyed in the first place. But after fighting with them, Ku realised that they might have actually met their match, instead of being frustrated however, they were excited. It is said that their battle shook the very core of the planet. They are a little frustrated however, so they killed the human that held the magical creatures captive previously defeated by Grey and Carter and dropped his items in front of their doorstep, note that it is a type of tradition to show your goodwill by stealing something from someone your recipient dislikes, though not so much about the killing part.

The next time they met, was when Ku manipulates the first batch of humans victims, enhanced their magic and lied about more power driven from the earth's core, almost causing the end of the world, Grey, Carter, Stella and Lazarus, a magically gifted child Grey was teaching stopped them. Ku jokingly called it cute and left him alive and even saved him from the humans they manipulated. After the humans were defeated, they left and as a gesture of another good will, killed the family of the humans who were abusers. The humans called them a hero and this started the teachings of sorcery, because Grey didn't know where to hold the humans, they were just held in a house, while no one escape, many outsiders snuck in to learn magic from them.

The first time they fully cooperate with each other was the time Ku realised that Wakana's grave was empty, they immediately went to Earth, they saw the Symbi that was born out of their cousin's grief, it was enough to give birth a Symbi. Because they weren't able to defeat the Symbi themselves, they turn to Grey for help, not because they want to save Earth but if they destroy the planet, Grey and the others would die and being the last Papilios in the universe, they don't want them to die. They manage to manipulate Lazarus to sacrifice himself to defeat the Symbi. Grey noticed but can't do anything about it given they don't have the power to defeat the Symbi.

Ku finally has the ultimate weapon to get rid of the measly planet that has always gotten on their nerves, a missile that was meant for another planet, has its course changed by Ku's hacker friend, they warned Grey in advance, thinking that they'll just move to another planet but they didn't expect them to face on the weapon. They realised that the very Immortal that exiled their cousin had told Grey to move a full on moon in the path of the weapon. Grey had finally confronted Ku about their actions but Ku didn't regret it, they fight again, this time Ku out powers Grey because Ku had reached their level 4 form but because of the Immortal interference, Ku had no choice but to leave. Grey had turned a little defensive when Luna almost took Ku, that didn't go unnoticed by Ku which made them feel something alright. This all happened during Grey's birthday hence why it's named that way.

Ku was approached by Luna for the second time, this time to warn instead of chase after Ku, one, because they technically haven't used any dark magic... yet... secondly, there was a slim chance that Grey could die if Ku didn't go and be present. Ku didn't know what they meant but Ku just so happened to be with a friend, which they brought given anything that can kill a Hubiin wasn't great news. But they arrived only to find out that there was nothing that was lifethreatening, at least to the eye. In order to release everyone from the last door, Grey offered themselves up to the room that was said to give people power but of course the room does the complete opposite, Ku realised and offered themselves up instead but Grey beat it to them. Ku thought that they had failed but it when the door opened, Grey was revealed to be alive and well. Ku asked Luna while Grey was in a coma what they did to save them and Luna confirmed that Ku did save them, but didn't say how

Huehuehue it's one of those 'reason to live' moments but ofc Ku doesn't know, only Grey realised but didn't believe it LOL

Because of blackmail, Ku was forced to help a psychic find Grey and their siblings, Ku cannot have second thoughts even though they are very reluctant, but was secretly happy whenever their younger manage to out smart the annoying human, which, irritated the psychic of course, before they could take action however, Carter managed to trick her into going into the mansion where Grey kept those who abused magic and let them handle the psychic... or well, just let them recruit her into their little club. Ku dissaproves after seeing that humans can get crazy ideas but the siblings weren't too worried. Ku didn't know how to feel about Grey being magicless and was quite annoyed when they were clueless about everything, but they guessed it was better than them being mind controlled.

While hunting in a forest, Grey was knocked out by a seemingly innocent looking phoenix. Ku was again, warned about Grey being in trouble and had no choice but to return to earth... again, this time Ku only managed to find Stella because Carter is off adventuring again and Ku's appearance might cause a scene and Ku didn't exactly want Carter dead so interrupted Stella's search for her great grandson, a puppeteer had Grey captive and planned on using them as a puppet. There seems to be a common theme throughout the 11th century... this becomes a gag where their siblings knows who actually saved Grey when Grey had always thought Ku has been causing mischief and their siblings were the ones saving them.

The god of destruction, a self proclaimed title but a deserved one given that this guy can destroy planets with a snap of his fingers. Again, another "full proof" way of getting rid of Earth. But of course, Grey has been working on a way to hide the entire planet from any prying eyes, given technology wasn't so advanced yet, he glossed by earth.

There has been disturbing deaths that have been occuring in a town, while Grey was investigating, they fell into a magical trap that prevents them from Summoning anything. (Ku... I think Earth is more dangerous than the outside world)