ஆடு புலியானாலும் ஆடுதான்
Aadu puliyaanaalum aadu thaan
Meaning
Even dressed in a tiger's skin, a goat is still a goat - pretence can never truly hide one's real nature.
Story
An actor who played a tiger on stage tried to carry that same swagger off-stage too. But the moment a real crisis arose, his natural timidity showed through. The costume had changed - the character underneath had not.
Reader's Note
Appearances fade eventually - what's underneath is what always shows through.