Understand the rules and power dynamics of the manga world. Know who the allies and enemies are. Also, keep an eye on hidden plot devices that could help or hinder you.
To survive as a villain in a BL manhwa, you have to be strategic. Understand the weaknesses of the heroes and exploit them. Also, build alliances when it suits you, but be ready to betray them if necessary.
BL in manga refers to Boys' Love. It's a genre that focuses on romantic and emotional relationships between male characters. Usually, it shows deep affection, sometimes with a touch of drama and passion.
One should stay low - key. Don't draw too much attention to yourself as an extra. Just do what your role requires and blend into the background. For example, if you're an extra at a party scene, just mingle a bit and don't interfere with the main characters' interactions.