Nothing to do with speedrun but...

Twisted Metal: Black all takes place in Needles Kane’s/SweetTooth’s mind. SweetTooth is the other personality of Marcus. Since SweetTooth is the stronger personality, Marcus is stuck in SweetTooth’s mind, where everything is dark. Every character’s personality and story is a representation of how SweetTooth thinks or something he has done in the past.

JUNKYARD DOG - Being betrayed BRIMSTONE - Lies of religion OUTLAW - Ineffectiveness of the law MR. GRIMM - Regret for a horrible act/Addiction to a horrible act ROADKILL - Forgetting your old life CRAZY 8 - Revenge against someone that has blinded you physically or mentally SPECTRE - Never finding love/Being an outcast/Selfishness DARKSIDE - Loss of innocence SHADOW - Friendship/Avenging someone important to you YELLOW JACKET - Broken family/Legacy after you die AXEL - Guilt for someone’s death WARTHOG - Removal of remorse MANSLAUGHTER - Demons/Intruders MINION - The biggest obstacle

The only ones who are aware of their presence in SweetTooth’s mind are Marcus, Black/Manslaughter and Calypso.

Minion is Marcus in SweeTooth's mind. That's why when we play with Minion we see those messages in codes "I DON'T THINK THIS IS REAL". "I THINK WE ARE TRAPPED IN HIS MIND" and so on.

Black is a demon who was sent by his master, from the real world, into SweetTooth’s mind to kill the Calypso in SweetTooth’s mind.

In the real world, Twisted Metal is an actual competition. The original Twisted Metal, 1995 (also Twisted Metal 2 and Twisted Metal Head on) is the real world.

Black’s master is the real Darkside, Mr. Ash/Darkside from Twisted Metal (1995). Mr. Ash is the devil.

Calypso obtained his powers by stealing Black from Mr. Ash and using Black’s demonic power to grant the wishes that the winners of the contest ask for. Since Calypso is present in SweetTooth’s mind, he used Black’s power to transport from his real body to his body inside SweetTooth’s mind and hides from Mr. Ash there, while remaining aware of where he is. Since Black is also present in SweetTooth’s mind, Mr. Ash sent Black from his real body to his body inside SweetTooth’s mind to kill the Calypso there. Since Calypso does not control Black in SweetTooth’s mind, Black is able to follow Mr.Ash’s commands. Since Calypso is aware that he is in SweetTooth’s mind, being killed by another aware person would kill him in the real world also, which is why Mr. Ash sent Black to kill him there. Mr. Ash cannot go himself because he does not exist in SweetTooth’s mind, which is why Calypso chose to hide there.

SweetTooth does not notice Marcus, Black and Calypso being aware because SweetTooth sees his imagination as the real world.