This command will disable combat AI for all NPCs in the game. When combat AI is disabled, NPCs are unable to engage in anything combat-related (so they won't be able to attack you). It is not possible to toggle combat for a specific NPC.
tcai
tcai
This is the only way this command can be executed. The above command would toggle combat artificial intelligence for everything in the game.
ToggleCombatAI
ToggleCombatAI is simply a longer version (alias) of the TCAI command - it has the exact same function.