Hellspawn is when he was mean and bad, and Spawn is him in the future because he was kidnapped and put in a brothel (they broke him, beat the "hell" out of him), Jacob got kidnapped when he was "Hellspawn" and during that time he and Aiden were having a falling out.

After Spawn escaped and made it back home, he wasn't the same anymore. He was quiet and close off, always being away from people, especially if he hurt them in the past.

You and Aiden were talking in the living room while Spawn was in his room. He hasn't left his room for minutes, but you understand why he didn't leave.