Why are u surprised about a North Indian being a foreigner in South India. Do you assume that it was ONE INDIA before british came. The INDIA we know today is a collection of many nations/kingdoms spread over this subcontinent.
North and South are different. We do not want to FIGHT over it, or be enemies, but atleast acknowledge it. in same way, the NORTH EAST is alien to mainstrean India. The sooner we acknowledgeit, the better.
this INDEPENDENT INDIA is only 50-60 year old and this forcefull collection of nations only 200-300 yrs old. otherwise we are like EUROPE...independent nations.