Xilo (Earth-616)

Origin

He was one of the Thresholders from 2 billion years ago and one of the two who survived Threshold's downfall, alongside Okkara.^[9][12] A mutant in the form of an insect collective, he had persisted despite going through many changes and many names.^[2]

Known, as the First Defender of the Broken Land, he apparently stayed with Okkara and protected it for the next 2 billion years. He was present on the island several thousands years ago when an enemy attacked the island and cleaved it in two new beings, Krakoa and Arakko.^[13][14]

Arakko in Amenth

He joined other mutants who went with Arakko to Amenth and remained with them for thousands of years.^[15][14] He became a member of the Great Ring of Arakko, the ruling body of the new island, and occupied the Seat of History at the Table of Dusk. As the chief historian, he was consulted on matters of lore, he recorded and decided the history of Arakko.^[6]

Details of his life for thousands of years on Arakko are unknown. At some point he started to use the name Stulgid,^[8] and still used it when Arakko with all of its inhabitants returned to Earth, after the tournament between mutants of Krakoa and Arakko.^[3] Shortly after, however, he changed the name to Xilo Who-Was-Stulgid.^[6] and then to just Xilo.^[5]

Planet Arakko

Because his powers allowed him to shape and manipulate soil and stone, Xilo was recruited by Isca the Unbeaten and Magneto to help terraform Mars to transform it into new home for Arakko. Xilo used his power to consume and pass the soil of Mars, enriching it and helping make the planet viable for life. When the terraformation of the planet was complete and Arakko was moved to Mars, Xilo used his powers to create the Valley of the Fallen, carving giant statues of Apocalypse and Genesis in honor of the mutants who had fallen in the wars of Arakko.^[5]

When the Great Ring of Arakko voted on returning to Amenth to war alongside Genesis or to remain on Planet Arakko in peace to build a new life, Xilo voted for war, but the vote ended in stalemate, so Storm, new regent of Arakko, used a second voice, the voice of Arakko itself, for peace, so they remained.^[2][16]

While searching for candidates to replace Magneto on the Quiet Council of Krakoa, Storm discussed the topic with Xilo, Sobunar, and Lodus Logos, but they all refused, seeing it as an insult to take a council seat without a fight.^[17]

War with Eternals

When Eternals waged a war on the mutants, majority of them concentrated on the Earth, but Uranos was sent to attack Arakko. He first attacked the Great Ring. Xilo was gravely injured, his body mass reduced to 13.5% and in result he lost millennia of eye-witnessed history. To survive, Xilo hid himself and Lodus Logos until Uranos left the Ring and went to massacre other parts of the planet.^[10]

After the end of war, Xilo contemplated on the great lose of memories. He lost so much of who he was that he was no longer Xilo, he had no name anymore and had to learn a new name for his new self. He decided to call himself That-Which-Was-Xilo in meanwhile.^[11][4]

The Great Ring gathered to judge Isca the Unbeaten's action of killing another councilmember, Idyll III, at the start of Uranos' attack. Ora Serrata, the Seat of Law, had no law fit for such situation, and That-Which-Was-Xilo had lost a large part of historical records, and couldn't say if such a situation happened before. Isca gloated over them not having law or precedent to judge her, but she was still ousted from the Great Ring.^[18]

Genesis War

Not long after the end of war with Eternals, Genesis returned to Arakko and criticized the Great Ring for its failure. That-Which-Was-Xilo observed Genesis's actions and words, she was once a big part of his recorded history, but as those memories were lost now, he wasn't able to predict her actions anymore. That-Which-Was-Xilo decided that to survive in his reduced form he should fuse with someone. He sided with Storm's faction and they all were teleported away by Lactuca, who decided to give them a chance to prepare for the Genesis War. After thinking about the candidates to fuse with, That-Which-Was-Xilo stopped his choice on the Fisher King, because both of them have no name anymore.^[4][7] Xilo fused into left part of Fisher King's body, and remained mostly dormant, allowing Fisher King to retain his freedom and personality and act on behalf of both of them. Fisher King provided tactical advises to Storm's faction during the War, while Xilo provided him with unclear warnings by squirming the worms of his body within Fisher's blood, bones and heart.^[8][19]

In the final battle of the Genesis War, Ora Serrata was blinded by Sunspot, Fisher King used this opportunity to get closer to her. Xilo left his body and took control over Ora Serrata instead, uniting seats of Law and History as Xilora. When Storm defeated Genesis, Lycaon wanted to continue the battle, but Xilora killed him and proclaimed the end of war.^[1]

Xilo is an Omega Level mutant^[5] in the form of an insect collective able to act as a single being or separate into seemingly innumerable tendrils.^[5][2] His known mutant weapons include:

• Earth Manipulation: Xilo was able to terraform and shape earth to his liking. During the terraforming of Mars, he merged with the planet itself to change the soil, supplying it with nutrients, elements, and minerals. He also created minuscule biotic life allowing Mars to support a breathable atmosphere.^[5]
• Immortality: As an insect collective, Xilo can replenish and replace parts of himself allowing him to persist for billions of years.^[2][9]
• Tendrils: Xilo's tendrils are powerful enough to scour a human to bone in seconds.^[10]
• Possession: Xilo can physically merge himself into the body of another being and take partial or complete control over them. He does this by replacing their flesh with his own, and once he leaves, the host will die from the injuries sustained by losing their flesh, as it happened with the Fisher King.^[7][1] While controlling another mutant, Xilo can use both his and their powers.^[1] The level of control he has seems to vary from host to host. When he merged with the Fisher King, Xilo was mostly dormant. The Fisher King was the one who talked and acted, and retained his original personality and freedom, while Xilo only occasionally provided warnings to the Fisher King.^[8][19] However, when Xilo merged with Ora Serrata, he was the one in control instead.^[1] The reasons for it are unknown, but likely either depends on Xilo's intentions, the host's willingness, the degree of fusion, or all of the above; the Fisher King was willing to merge, and they merged only partially, while Ora Serrata was taken over forcefully against her will and they fully merged.

When Xilo's body is damaged he loses parts of his memories forever.^[10][11]

• Like most Arakkii, Xilo appears to have disdain for Tarn the Uncaring.^[20]
• Despite being a collective of insects,^[2] Xilo acts as a single being and refers to itself "I", rather than "we".^[10][11][1] Xilo has been described using both "they"^[2] and "he"^[10][8] pronouns with no known preference.
• Xilo is apparently not his real name, as he changed it on multiple occasions. According to Steve Orlando (the writer of Marauders (Vol. 2) #12), after surviving the extinction of the Threshold he was injured both mentally and physically so severely that it took him millions of years to heal and regrow from almost nothing, but "what's healed may be more like a blank slate",^[12] so he apparently have little to no memories about the Threshold and most likely no longer even remember his original name.

• After he was seriously injured in X-Men: Red (Vol. 2) #5 Xilo was depicted much smaller in all of his appearances up to X-Men: Red (Vol. 2) #13. In X-Men: Red (Vol. 2) #14, however, he was depicted big again, as he originally was, without explanation.
• Xilo, a worm-like creature, terraforming Mars appears to have been based on the Sandworm from Dune.^[21]