Killing Zoe/WMG

Zed gets AIDS when
Zed has a big, bleeding open wound. It's not covered at all. When  in front of Zed,   blood get splattered all over the place. Possibly in Zed's wound. And since you know him and Zoe are going to screw again later,  may end up being right when he said he'd "fuck her up the ass and give her AIDS."

Killing Zoe takes place in the same universe as Reservoir Dogs
Because Zed was in Paris at the time of the heist, Joe couldn't find a safecracker he trusted. He decided that instead of a smart, cool head, he'd use dumb muscle. This backfires when his old buddy Mr. Blond goes off the rails and shoots the place up.

Killing Zoe takes place in the same universe as Pulp Fiction
And Zed is the twin brother of Lance. When the two were growing up down the street from Eric, it was Lance who first gave Eric heroin.
 * For added fun, what if for the entire film Eric was shooting up Choco, the same heroin the nearly killed Mia!