Rogue Angel -> Angel that will use some of their money in order to get a bit of stock which they then use in a minority shareholder lawsuit in order to try to leverage that into a larger amount. Start-ups can't have distractions like that so people that pull that stunt can hold you over a barrel. I've seen this up close and it isn't pretty.
Investment bankers are not bad by definition, but on the whole they're worth a lot less than they give themselves credit for. They presume to be an in-dispensable part of the deal universe but in actual fact they can be as much of a hindrance as they can be a help. Oh, and they always want to be paid, even when they don't perform at all.