A second season of Monarch: Legacy of Monsters has been confirmed, and the new setting of the series promises to answer several long-standing mysteries surrounding Legendary's Monsterverse. Monarch: Legacy of Monsters fills out the world created by the Monsterverse movies with a story about two siblings who investigate the impact of their father's work in the titular organization devoted to the study and tracking of giant monsters. The second season has the chance to truly fill in some crucial blanks about the universe and its monstrous inhabitants.
The ending of Monarch: Legacy of Monster's first season revealed that Keiko Randa was still alive, having somehow survived her grave circumstances, eking out a living in the interstitial dimension that joins the surface of the planet with the Hollow Earth known as Axis Mundi. This strange world has a significant time dilation effect that causes the cast, along with Keiko, to resurface in 2017, 2 years later for the modern characters and 58 years later for Keiko. This came alongside the ominous discovery that Apex Cybernetics, the company behind Mechagodzilla, has established a research base on Skull Island.
8 How Apex Used Ghidorah’s Skull
This valuable cranium was the key to operating Mechagodzilla

The Monsterverse ended up incorporating an origin similar to the classic Toho Mecha King Ghidorah for their Mechagodzilla incarnation, powering his tremendous processing load via one of King Ghidorah's skulls. It's revealed in Godzilla vs. Kong that King Ghidorah's lingering psychic imprint left behind on his corpse was a powerful enough force to form the basis of a control system for a massive artificial kaiju. Without the processing power of King Ghidorah's latent neural pathways housed within his skull, it's likely that there would be no way to bring the cybernetic beast online.
Considering the size and scope of Mechagodzilla, it stands to reason that Apex would already have been working on it by 2017. Godzilla: King of the Monsters teased the creation of Mechagodzilla by showing Jonah purchase the huge bone after it was dredged up from the sea floor by fishermen. Season 2 of Monarch: Legacy of Monsters could very well show exactly how Apex was able to discover the lingering spirit of Ghidorah within his skull and use it to power their infernal creation, perhaps using the remote Skull Island base as a forward operating center.
7 How Kong’s Growth Spurt Happened So Dramatically
Kong's growth from the time of his first movie appearance is still unprecedented

One often-forgotten change made to the Monsterverse's King Kong between the time of his first appearance in the 70s in Kong: Skull Island and his modern incarnation in Godzilla vs. Kong is his sheer size. While Kong is certainly a huge creature in Kong: Skull Island at just over 100 feet tall, his size still pales in comparison to Godzilla's first appearance in the Monsterverse. In order to make things fair, Kong's height had to be scaled up dramatically in-between films, being around Godzilla's size by the time of Godzilla vs. Kong.
Thanks to Kong's cameo in Monarch: Legacy of Monsters at the tail end of the season 1 finale, it's all but certain that he'll have the same slow, lingering presence in the second season as Godzilla had in the first. After all, the next season will almost surely take place in his home turf of Skull Island in 2017. Perhaps this place on the timeline can finally describe exactly how Kong was able to achieve such a massive growth spurt over the course of 40 years after ostensibly being the same height for centuries.
6 What Happened To Charlie
Another of Skull Island's castaways kidnapped by the Iwi

Season 2 of Monsterverse: Legacy of Monsters won't be the first Monsterverse spin-off show to be set on Skull Island. Enter the animated series simply titled Skull Island, one of the more glossed-over yet still very canonical entries in the Monsterverse. Skull Island explores the titular land as it appeared in the 90s through the perspective of a cast of castaways, mostly younger kids who suddenly have to contend with the location's terrifying megafauna as well as Kong himself. Skull Island ends somewhat abruptly, with the fates of many characters left up in the air.
One of the biggest glaring mysteries left over from the cartoon is what happened to Charlie, one of the series' main protagonists. While still just a kid, Charlie ends the series being kidnapped by the native Iwi people. The Iwi people are later explained to have been all but wiped out on Skull Island due to a series of floods, with Jia Andrews as the sole survivor. Perhaps season 2 of Monarch: Legacy of Monsters can take advantage of the Skull Island setting to determine whatever happened to Charlie after he was captured.
5 How Apex Managed To Capture A Skullcrawler
The cybernetics company accomplished some impressive feats

The primary enemy of Kong in his first Monsterverse appearance in Kong: Skull Island were the Skullcrawlers, giant ophidian monsters with creepy skull-like faces responsible for ravaging the island's ecosystem. The Skullcrawlers are nowhere to be seen on Skull Island by the time of Godzilla vs. Kong, but the same film later reveals that Apex Cybernetics was able to capture one and use it as a warm-up test for Mechagodzilla. The film's human cast can only watch in horror as Mechagodzilla demolishes the fearsome creature.
Since Skullcrawlers are native to Skull Island, 2017 might've been Apex Cybernetics' only chance to capture one of the monsters while maintaining a forward operating base there. Promotional images for Monarch: Legacy of Monsters season 2 revealed a trashed Apex lab, obviously destroyed by some native creature. Perhaps the series can determine how exactly Apex managed to restrain and withhold one of the beasts in the first place, and the many lives it may have sacrificed in order to do so.
4 How Keiko Will React To The Modern World
The lone Axis Mundi survivor will have a lot to catch up on

The ending of Monarch: Legacy of Monsters saw the cast shocked as they emerged from the Axis Mundi into 2017, with 2 years having passed in the course of a few hours for the modern characters. But the revelation must have been far more traumatizing for Keiko Randa, who spent 57 days surviving in the hostile environment's harsh conditions. When she was stranded in the strange dimension, the year was 1959, meaning that Keiko was essentially hurtled forwards in time by over half a century.
Of course, season 2 must explore exactly how the modern world will affect Keiko. The gradual erosion of the same social boundaries she faced as a Japanese woman in the 50s may be refreshing, but the sheer overwhelming existential overload of being flung into the future won't be easy. More personal ramifications to Keiko's journey may be explored as well, such as hearing about her granddaughter Cate's Godzilla-related trauma after championing the creature herself.
3 Where Shaw Was Transported
It's quite unlikely that Shaw is dead

Injecting a healthy dose of star power into Monarch: Legacy of Monsters season 1 was Kurt Russell's Lee Shaw, a military colonel working closely with Monarch. After managing to find Keiko in the Axis Mundi, Lee sacrifices himself so that her and the others can escape, having to repair the reconnaissance pod manually as the Ion Dragon and Godzilla fight. In the resulting chaos, Lee falls into the Vile Vortex of the Axis Mundi, presumed dead.
Considering a body is never explicitly shown, it's more than likely that Lee wasn't killed, but transported to some far-off dimension or even another location on Earth. After all, the Vile Vortexes are the portals connecting the Axis Mundi to the Hollow Earth and the surface world, meaning that there are endless possibilities for where Lee could have been teleported to. That being said, if there's one thing that may keep Shaw dead, it's the expense of Kurt Russell's star power.
2 What Led To Ren And His Father’s Ideological Divide
The apple fell quite far from the tree

The Monsterverse certainly loves to indulge in messy family drama, and one of the more underrated intrafamilial conflicts of the series is the vast ideological gulf between Dr. Serizawa and his son, Ren. Dr. Serizawa is one of the biggest proponents of the Titans in Monarch, infamously saying "Let them fight' rather than try to artificially intervene in Godzilla and the MUTOs' conflict. This love for kaiju ends up getting him killed, sacrificing himself to save Godzilla in Godzilla: King of the Monsters, but in doing so he gains the rare honor of Godzilla's acknowledgment.
Meanwhile, Ren ends up siding with Apex Cybernetics, being chosen to be the pilot of Mechagodzilla in Godzilla vs. Kong. It would be interesting to see the two of them explore their relationship in 2017 with the next season of Monarch: Legacy of Monsters. The show could finally explain how the son of someone like Dr. Serizawa came to have such a disdain for kaiju as a whole, with his father's death likely only being the straw that broke the camel's back.
1 How Mothra Was Discovered
The one major Titan still lacking an origin story

One of the most important Titans in the Monsterverse is none other than Mothra, the massive insectoid queen of the monsters and Godzilla's ancient ally. In the Monsterverse timeline, Mothra first appears in the flesh in 2019 with her role in Godzilla: King of the Monsters. Here, she hatches from her long-monitored egg and matures into a larval form, before eventually mutating once again to become the massive winged kaiju of Toho fame.
Mothra is teased a few times before her egg is first shown on-screen, coming up in classified Monarch cave paintings in Kong: Skull Island and having her name on an aquarium label owned by the Brody family in Godzilla. But the exact process of how Monarch was able to determine the location of her sacred egg and set up a monitoring station around it remains a total mystery. It would be interesting to see Monarch: Legacy of Monsters season 2 explore this in some capacity.