Carrion/Chronology

Demon Lord Attack Arc
Having participated in Kleiman's Puppet Demon Lord raising project, Carrion was, like Milim, disappointed that it got disrupted, however the records of the final moments before Gelmud's death left Carrion intrigued, especially upon seeing images of Ranga. He gladly went along with Milim's idea of repealing the non-interference agreement for the Great Jura Forest and sent one of his Three Beastketeers, Phobio into the forest as his representative.

Things did not go as Carrion wished, however, as Phobio not only ran into and angered Demon Lord Milim, but also caused a conflict with the Tempest residents themselves, and even got conned by the Moderate Harlequin Alliance into taking Charybdis' core into his body, causing him to transform into Charybdis himself.

Sometime during the battle between Charybdis and the Tempest-Dwargon Alliance, Carrion arrived at and tried to observe the battle without being detected, though not being able to see much of it. Eventually Milim incapitated Charybdis with her Drago Buster after which Rimuru started an magical surgery to separate Charybdis' core from Phobio's body and eventually succeeded.

When the battle and its aftermath were over, Milim, who had easily detected Carrion, called out to him, causing Carrion to reveal himself. At first, since Carrion didn't recognize Rimuru's Slime-form, Carrion had doubts about Rimuru as a Slime, leading a nation, but upon witnessing Rimuru's aura, he realized that Rimuru was at the level of a Demon Lord Seed and therefore was most likely the human-looking individual who defeated Gelmud and likely also devoured the Orc Lord, which Rimuru confirms to him. Upon clearing that up and seeing Rimuru standing his ground, Carrion laughed, stating that he understands why Milim took a liking to him. Then he apologized for his subordinate Phobio's actions and thanked Rimuru for sparing and even saving Phobio despite what he had done and told Rimuru that he is in his debt and willing to compensate him, upon which Rimuru asked for a non-aggression treaty and engaging in diplomatic relations, which Carrion notes that is less than he expected, but agrees to it anyway, swearing that from that day forth, the Beast Kingdom Eurazania won't lay a hand on the Jura Tempest Federation.

After the discussion, Carrion swiftly punishes Phobio by slamming his head on the ground and not letting him heal his resulting bleeding. Then take bids farewell to Milim and Rimuru and teleports away with Phobio in tow.

Human-Monster Interaction Arc
As promised, Carrion sent a delegation consisting of Albis, Suphia, Grucius and some other Beastmen to Tempest, while at the same time receiving a delegation from Tempest's side. After Tempest's delegation, Rigur and Benimaru, arrived in Eurazania, Carrion ended up having a sparring battle with Benimaru and easily won, but Benimaru also managed to score a victory against Phobio in turn.

The negotiations went well on both sides, and soon after Eurazania would start exporting fruits to Tempest, while importing Tempest's processed alcohol in return.

Demon Lord Awakening Arc
One day Milim arrived above Eurazania's capital, declaring war, and announcing her upcoming attack a few days later. Taking this declaration very seriously, Carrion ordered the capital's evacuation, only keeping his most trusted subordinates with him. When Milim arrived for the battle, Carrion confronted her alone. But after some exchanges, Carrion's strongest attack only managed to make Milim's hands feel slightly numb, which she "rewarded" by demonstrating her Drago Nova attack, which pulverized the entire capital. Afterwards, Carrion seemingly got his neck sliced by a suddenly appearing Frey, leaving Carrion presumed dead.

The Octagram Soars Brightly Arc
Carrion survived and his death was just staged in order to fool Kleiman. Milim and Frey then explained the plan of tricking Kleiman to him upon which he agreed to take part in the plan by donning a disguise and participating in the Walpurgis Banquet as Frey's subordinate. Carrion did not do anything significant during Walpurgis other than revealing his identity at one point. The plan to trick Kleiman turned out to be mostly redundant, as Rimuru resolves his grievance with Kleiman himself.

But upon seeing the battle between the fully awakened Rimuru and the pseudo-awakened Kleiman, Frey realized that she is not up to par with the rest of the Demon Lords and decided to retire from her Demon Lord posts, while similarly Carrion having lost to Milim in battle one-sidedly no longer felt able to see himself as an equal-in-status Demon Lord with Milim and therefore also retired, both Frey and Carrion becoming Milim's aides as a result.

Territorial Seizure Arc
From Tempest, Geld's construction team came in order to help building a new capital for Eurazania which became a part of Milim's Domain with Carrion still being the nation's king despite having become Milim's subordinate.

Monster Capital Opening Festival Arc
Carrion and Frey came to Rimuru City alongside Milim in order to participate in the "Monster Capital Opening Festival" that was being held for Tempest's official debut on the international political stage.