Here is a link to a lecture by JWG that is about the relationship of Mars to Pluto: http://schoolofevolutionaryastrology.com/school/articles/the-mars-pluto-interface
In EA Mars is the ruler of Aries, Ascendant, and the 1st House. So when you see the Nodes in Scorpio that does not mean that it has a co-ruler with Pluto. As you will read in the article Mars, the 1st House, and Aries all correlate to how the desires of the Soul get instinctually acted up via the current life ego, Moon, and the subjective consciousness therein. When the rulers of the N. and S Nodes are opposed it generally means the Soul must throw off some existing inner dynamics, to inwardly oppose them which also manifests as circumstances creating apparent opposition to the Soul's intentions as symbolized in those planets, Nodes, in order for the Soul's evolution to proceed. Any planets in opposition, including the N.Node also correlate with this evolutionary need to throw off something, to oppose it, in order to evolution to proceed via those dynamics.
God Bless, Rad