A R Rahman has done some nice background pieces in songs which are basically a conversation between either 2 instruments or an instrument and a vocal. These are not question and answer types but more like a real conversation. Listen to 4 such conversations below. Interestingly all of them are towards the ending of the respective songs. It is more like a postlude.
The 1st one is "En swasa kaatre" from "En swasa kaatre". Nice conversation of veena and chitra's voice. I love the veena in this piece. The chord and bass backing is also very good. I think this is in Nilambari raga. Please correct me if I am wrong.
The 2nd one is "Azhage sugama" from "Paarthale Paravasam". A nice conversation between piano and violin. Violin is played by Ganesh I believe. I read that it is a mixture of dwijawanti and sahana ragam.
The 3rd one is "Uyirum Neeye" from "Pavithra". Veena and violin converse here in Khamas raga I think.
The 4th one is "Netru Illatha Maatram" from "Pudhiya Mugam". Nice sitar and flute combination. You can also listen to a veena in the third line. This is the same piece played in the first interlude. But in the first interlude it is a sitar and veena conversation. And at the end, the sitar piece is the same, but a different flute response. Flute must be by Naveen.
Let me know if there are other similar songs by ARR. I will also put a separate post on such conversations in Ilaiyaraaja's music. So let me know the relevant song interludes that come to your mind in IR's music.