2 power sources are connected together... for simplicity sake.

2 12v lead acid batteries, - to + and + to - where the wires meet where do the electrons flow? a simulator just says a short but what actually goes on here? the energy is way more intense than just a direct short.. so what's going on here?

If both batteries are in good nick this is just like shorting both of them out, the current's the same, the

voltage is all dropped across internal resistance and cable resistance dumping ~10 kW into both.

However if you don't fully short them out there is twice the voltage available to hold a DC spark, which

will then be ~4 times as powerful as one battery (but this is just a DC load, not a true short ciircuit!)

High power DC arcs are pretty stable (arc welding), especially at higher voltages, and the size depends on the

available power more than anything. The length of the arc can be longer with higher voltages, but

high power also helps.