What is Death Prophet's Role? (i.e. Support, Carry, etc.)

I played a game earlier where my Lion and my Warlock both refused to buy the flying courier even at 12 minutes in, telling me (Death Prophet) to do it instead. The Warlock said he needed the gold for a Refresher Orb (Yeah, that'll help the team...) and the Lion said I should buy it because DP is not a carry and she is "a ganker at best".

I laughed and responded "Me? A ganker? I don't have a single form of hard Crowd Control!" Lion said something unintelligible but I could make the words "muting you", warlock called me a douche and muted me too.

TL;DR: I just told a huge story as to why I want to know the answer to the title.