(after a verb or adjective) one who (is) ... / (after a noun) person involved in ... / -er / -ist / (used after a number or 後|后[hou4] or 前[qian2] to refer to sth mentioned previously) / (used after a term, to mark a pause before defining the term) / (old) (used at the end of a command) / (old) this
to chase / to pursue / to look into / to investigate / to reminisce / to recall / to court (one's beloved) / to binge-watch (a TV drama) / retroactively / posthumously