Brangaene warns Isolde that one of King Markeâ s knights , Melot , has seen Tristan and Isolde looking at one another lovingly . BrangÃ ne warns Isolde that Melot , one of King Markeâ s knights , has seen the amorous looks exchanged between Tristan and Isolde and suspects their passion ( `` Ein Einz ` ger war 's , ich achtet ' es wohl '' ) .