Hey!

I just joined, and also come from a roleplaying email background. I also love dark themes, with most of my characters being mentally unhinged, capable of murder, and prone to their vices. 

I really like just about everything on your list, but especially the
>> rival gang members
>> cop x criminal
>> mob boss' daughter x street gangster
>> addict x dealer 

I figured I'd post here anyway, but going to PM you like you suggested LOL. Would love to try a roleplay to see if our styles mesh.