Limited support
This feature is only present in Portal 2: Community Edition and Portal: Revolution.

npc_focus

🟦 Executable on Server only

npc_focus

Displays red line to NPC's enemy (if has one) and blue line to NPC's target entity (if has one) Arguments: {npc_name} / {npc class_name} / no argument picks what player is looking at

Warning:

This is a cheat command and can only be used when sv_cheats is set to 1.