In a parliamentary system, there is a fusion of legislative and executive functions. The real executive i.e. the Prime Minister and Council of Ministers is drawn from the Legislature. There are no separate elections for the post of Prime Minister and other Ministers. The Prime Minister and the Ministers play a dual role i.e., they are part of both Legislature and Executive. Thus, they also attend Parliamentary sessions.
The leader of the party or group which commands a majority in the legislature is invited by the nominal executive (President) to form the government and assume the post of Prime Minister. The Ministry stays in power only as long as it enjoys majority support in Parliament. The lower house of the Parliament in England (House of Commons) and in India (Lok Sabha) can pass a vote of no-confidence against the Ministry which means that the Prime Minister and his/her Council of Ministers must resign. This is due to parliamentary sovereignty. Thus, the executive is subordinate to and responsible to the Parliament (legislature).