And thus began the story which Dark Reign is essentially ripping off.
Characteristic of Mackie that we never find out the connection between Mad Jack & Marla. Sure, we know that Jack was sometimes a remote-controlled robot, sometimes the original Mysterio's long-lost sister, and sometimes the fake Mysterio who Jonah had once hired and then not released from jail. That's definitely who we see hovering over the hospital bed - but apart from that, we get nothing.