Isaac Clarke - is the main playable character and protagonist of the game.Norton and Carver then left to find Clarke, with the Inner Circle following them. Before leaving, Ellie asked Norton to find Isaac back at New Horizons. After Ellie traced the Marker signals to a distant planet, Ellie headed for the planet, Tau Volantis, with Austin Buckell and Jennifer Santos. After escaping the planet, the group was followed by the Inner Circle. However, he was rescued from certain death by Captain Robert Norton and Ellie Langford. Carver's family were then transformed into Necromorphs and he was forced to destroy them to survive. John Carver's wife and son were murdered by Jacob Arthur Danik, the founder and leader of the Inner Circle. Recently, the group attacked the Marker Test Lab on the planet Uxor. Apparently, these attacks have been so thorough and so devastating that EarthGov has effectively been destroyed. Three years after the Titan Station incident, a radical Unitologist group known as the ' Inner Circle' has begun a reign of violent riots and have been destroying the Marker Test Labs on all major colonies to spread the Necromorph infection. Ellie left to figure out ways to stop the Markers while Isaac stayed in hiding and quickly regretted breaking it off with Ellie.

However, due to the events Isaac had witnessed and Ellie's ambition to stop the Markers, the two broke it off.

In that time, Ellie's lost eye was replaced and the two developed a romantic relationship. Isaac and Ellie continued to hide from EarthGov and resided on the New Horizons Lunar Colony, a city found on Earth's moon.

Isaac then escaped with mining engineer Ellie Langford after he destroyed the Marker, resulting in Titan Station's destruction. The Marker built by a delirious Isaac on Titan Station somehow 'activated', resulting in another outbreak of Necromorphs. After the events of Dead Space, EarthGov captured Isaac Clarke and harvested his mind for Marker blueprints in order to revive the Marker program, in which Markers are used to provide resources and power for the Human race.

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