[steely]

smells fishy and I think you're onto something. The key could be the Red Tape Blue Tape junctions of which I know nothing. They appear to be power distribution busses. I wish I knew where this 'tape' / junction was physically located for you. Blue is also associated with seat heaters, red with power seats.

You might try disconnecting the plugs under both seats and seeing if that helps in the isolation quest.
And/or with all power off, fuses 1 and 2 removed, buzz (resistance check) red to red/blu (fuse 1 to fuse 2 load side) to see if they are in fact common.