So the previous owners of this house decided to put two switches in a switch loop with two lights in the hallway. The house is old, so it was probably the "fastest" way to get two switches on the hallway lights, but because they are in a switch loop with the lights, both switches must be on for the lights to be on.
Currently the circuit is as follows:
Panel to a junction. One of the cables goes off to power, the other to lights (that have the same issue...). The branch in question goes to the two hallway lights in series, and at the first switch there's a hot white with common black. Then they ran 12-3 cable to another switch, capped the live wire (white) with the red, and included this other switch into the series (and just wired the 3rd wire to nothing...it literally runs from ground on one switch to ground on another).
I'm trying to imagine the best way to fix this and having trouble. I would want the common fixed to both switches, so do I need to drop 12-3 cable from the first lamp to the switch box, or is there something faster I can do?
Edit: Here's a mockup I quickly put together in Sketchup. The red dots are wire-nuts, the circular things are the lights, and the switches are self explanatory:
At this point, I think the proper thing to do would just be run a new circuit (with ground), and wire it properly as a 3-way switch. Would also be easier than messing around with this thing any longer.