Clark was eventually killed by Seegson Working Joe 937 after waiting outside an elevator for him.
While roaming through Sevastopol's empty halls, Clark recalls on how large mega corporations have caused several businesses, including his own, to close down, resulting in his wife and kids leaving him behind. Regardless, he is glad that they left the station. As he hears incoming footsteps from the halls, he panics and backs himself against the wall.
Fearing death at the hands of the Alien, Clark considers taking his own life with his two remaining bullets, but changes his mind at the last minute and instead to shoot whatever is coming. He fires and realizes that he has shot Ross, a human.
Clark regrets what he did and panics, throwing his gun away and stating that he didn't mean to kill anyone and that it was an accident. Assuming Ross is dead, Clark decides to take the Ross's weapons and move forward. As Clark is about to leave, he hears Ross crying for help, however the Alien suddenly appears from behind Ross. Clark leaves Ross behind and escapes via elevator, leaving Ross at the mercy of the Alien.
As the elevator opens, Clark is confronted by Joe 937, who tells him that he shouldn't be here and then proceeds to strangle him to death.
Personality and Traits
Clark was one of the many normal, average people on Sevastopol turned into paranoid and terrified survivors, desperately scavenging just to stay alive. He constantly repeated to himself that he is a "decent man" and that he never deserved to be in the position he was in.
Judging by how he reacted to accidentally shooting Ross, it's likely that he was an emotionally fragile person.