This movie is the literal definition of the topic. It showcases twins who are polar opposites. One is a rough aggressive brother (Annan), and the other is a timid, simpleton (Thambi).
Since "Annan Thambi" is a classic trope in Tamil movies (rivalry, misunderstanding, or ultimate sacrifice between brothers), here is the most iconic reference, a famous dialogue, and a short original story based on your request. annan thambi dialogue tamil work
"I might hit my younger brother... no one else has the right to even ask why. But if any outsider so much as touches my brother, I will be there to answer him, Sir!" This movie is the literal definition of the topic
மாலை நேரம். ஊருக்கு வெளியே இருக்கும் பெரிய ஆலமரத்தடியில் இருவர் அமர்ந்திருந்தனர். ஒருவர் கையில் வெறும் தேநீர் கோப்பை, மற்றவர் கையில் ஒரு சின்ன சூட்கேஸ். and the other is a timid