Upvote:2
Here are your visa requirements:
Hamburg - Istanbul; None, you will get stamped exit on your Schengen visa.
Istanbul - Bahrain; If you are departing from the same airport, none. If you are departing from different airports then you will need a visa for Turkey. Indian nationals can apply for an e-visa online at https://www.evisa.gov.tr
Bahrain - New Delhi (transit in Abu Dhabi); you will need a visa for Bahrain, as Pegasus does not have transit agreements with Etihad. You can get this visa online from https://www.evisa.gov.bh/ - you do not need a visa for Abu Dhabi as you will be in transit.