Warning: SPOILERS for Superman & Lois‘ Season 1 Finale – “Last Sons of Krypton”.
Superman & Lois season 1 revolved around the presence of X-Kryptonite in Smallville but here’s why the alien element is so abundant and can only be found in the Kansas hometown of Clark Kent (Tyler Hoechlin). Superman & Lois‘ finale saw the Man of Steel and John Henry Irons (Wole Parks) stop a Kryptonian takeover of Earth by Morgan Edge (Adam Rayner). Lois Lane (Elizabeth Tulloch) also helped save her son Jordan’s (Alex Garfin) mind from Edge’s Kryptonian father Zeta-Roh (A.C. Peterson).
The Arrowverse’s version of Superman takes a few important cues from Smallville, in that Lois and Clark moved back to Kent’s childhood home in order to raise their twin boys, Jordan and Jonathan (Jordan Elsass). Like Tom Welling’s Clark Kent, Tyler Hoechlin’s Superman splits his time between saving the world and running the Kent Farm with his family. But Superman & Lois also borrows the crucial plot device of Kryptonite being present in Smallville. In Welling’s long-running series, meteorites composed of the remnants from the doomed planet Krypton accompanied baby Kal-El’s rocket when it landed on Earth. Smallville was struck by a meteor shower that masked the arrival of Kal-El’s ship, and Smallville‘s assortment of Kryptonite was also an ingenious plot device to create “meteor freaks of the week” villains for teenage Clark to face in the early seasons of the show.
In Superman & Lois‘ canon, Kal-El’s arrival in Smallville after Krypton exploded in 1979 was also accompanied by Kryptonite meteorites. Some of the space rocks were the green Kryptonite lethal to Kryptonians, but it seems large deposits of X-Kryptonite dropped into Smallville and became embedded in the Shuster Mines outside of town. X-Kryptonite (or X-K) is a significantly different element; the variant Kryptonite is yellow in color and can imbue humans with Kryptonian-like abilities, although the effects are unstable and dangerous to ordinary natives of Earth. When Morgan Edge, who was really Superman’s Kryptonian half-brother Tal-Roh, learned of Smallville’s X-Kryptonite deposits, it made Clark’s hometown the epicenter of his and Zeta-Roh’s plot to use the X-Kryptonite and the Eradicator to turn humans into a Kryptonian army.
However, the fact that Tal-Roh also came to Earth from Krypton naturally begs the question of why there is no X-Kryptonite found in his landing point in the British Isles. The answer is that Zeta-Roh sent Tal-Roh to Earth before Krypton exploded and the man who would later give himself the name Morgan Edge beat Kal-El to Earth by a few years. Therefore, Tal-Roh’s arrival wasn’t accompanied by a meteor shower of Kryptonite since his homeworld hadn’t exploded yet.
Meanwhile, Tal-Roh’s life on his adopted planet was nowhere near as idyllic as Kal-El’s. The extraterrestrial Tal-Roh was hunted and imprisoned by the British but he eventually escaped and disguised himself as a human. But even though he became the wealthy and powerful Morgan Edge, Tal-Roh harbored a hatred of humanity for the way he was treated, and he was naturally envious of how his half-brother Clark grew up in Smallville and was embraced by humans as the heroic Superman. But part of what made Edge’s scheme so delicious was being able to use the X-Kryptonite in Kal-El’s adopted home against him and his beloved humans.
And yet, despite spending his formative years in Smallville, Clark was unaware that there was X-Kryptonite in the Shuster Mines until Superman & Lois season 1. The Department of Defense led by Clark’s father-in-law, General Sam Lane (Dylan Walsh), moved into Smallville and took control of the mines to secure the X-K, which caused a lot of conflicts with the local residents. Now that the dangers X-Kryptonite poses are well-known, efforts will be made to secure it so another Kryptonian-human body-snatching scheme can’t be attempted but it remains to be seen how X-Kryptonite will continue to factor into Superman & Lois season 2.