This was probably the first scene where Murtesim was kinda friendly with Merub! Before that he was always shown to be headstrong or in deep thoughts! The gaddi ja nasheen he was, with tge khandan being from him & him, not from khandan! Apni marzi ka malik etc.
Switching the light off was such naughty idea of him just to prove her "main kisi ke baap se nahin darti, Murtesim" wrong! 
