Mark Sim is the character in Season 3:Ultron Revolution.
|Chronological and political information|
One evening, the Avengers were battling Ultron in the Inhuman capital city of Attilan. The villainous Ultron had built a weapon designed to kill every being on Earth, but the Black Widow reluctantly switched the death ray for a Terrigen Crystal at the last moment. As a result, Terrigen Mist was dispersed across the entire globe. Haechi was one of the affected and, after going through Terrigenesis, he discovered he had gained super-human abilities.
After a disaster in Attilan which culminated in the destruction of the city, Haechi joined two other runaway Inhumans, Flint and Iso, that wanted to avoid Truman Marsh (secretly Ultron) mandatory registration. The Avengers were vehemently opposed to such a system and cut all ties with the government. So, Marsh created his own team of Avengers, the Mighty Avengers. One of their first missions was to intercept the three runaway Inhumans, which led to a fight between the two Avengers' teams. Ultimately, Captain America got seriously injured and the main Avengers were arrested. The only member who avoided arrest was Black Widow, who combined forces with Medusa And Black Bolt to rescue the Avengers. After getting away, Inhumans all over the world, including Flint, Haechi, and Iso, started to lose control over their powers, because of the registration disks and it was at this moment that Ultron revealed himself as Truman Marsh. 
Ultron then attacked the city with a robot army, but was eventually defeated by both the Avengers' teams and Doctor Strange. In the end, a New Attilan was build to host every inhuman who wanted a new home.
Season 3: Ultron Revolution
. "Captain Marvel"
. "Civil War, Part 2: The Mighty Avengers"
. "Civil War, Part 4: Avengers Revolution"