Tā shēngrén wù jìn, què duì lǎo péngyou hěn rèqíng.
He is standoffish with strangers but very warm with old friends.
Tips
usage
生人 most commonly means 'stranger' in everyday speech. In classical or formal contexts it can also mean 'a living person' (as opposed to the dead). 生人勿近 (shēngrén wù jìn) — 'strangers keep out' — is a common written warning.