Jǐ cìcháng tán hòu, liǎng rén jiànjiàn hùxiāng shìwéi-zhījǐ.
After a few long conversations, the two gradually came to see each other as confidants.
Tips
usage
知己 ('one who knows oneself') is a heavy word in Chinese - closer to 'soul mate' or 'true confidant' than 'friend'. Saying 视为知己 is a strong declaration of trust, not casual.
