It is clear that the actual struggle between the Dark One and the Creator is working in parallel to the sha’rah game. The Dark One has been manipulating Rand in an attempt to take control of him. Moridin in particular is intimately connected with this effort, which is why Rand sees him in his head (see p.235-236 of The Gathering Storm). He sees him in his head because when their balefire crossed streams in Shadar Logoth in aCoS, it created a link between them that has made them aware of one another. That is why Moridin is so pissed at Semirhage in this book, and why his hand is bothering him in the prologue. Also why he forbade them to kill Rand in KoD, and why Rand recalled the Ansaline Gardens when thinking of Moridin.
As for Moridin's intimate involvement in the effort to take control of Rand, it is probably Moridin's idea. RJ has stated in the QotW that the Dark One's perception of the world is strongly influenced by the Forsaken, of whom he clearly favors Moridin/Ishamael, which makes it more likely that Moridin's personal philosophy is behind the strategy of the Dark One manipulating the Dragon.

It seems to me that the only logical conclusion that can be drawn is that Rand’s body will be taken over by the Shadow, by Moridin in particular. Jordan, in the very first book, alluded to “myths” of a forgotten past that are certainly not coincidental – Materese of Ind (Mother Theresa of India) and Mosk (Moscow) and Merk (America) as giants who hurled spears at each other. At the same time, the iconography of Rand al’Thor is a complete inversion of our understanding of those symbols. Symbols, schmymbols. It is indicated by Min's viewing of Rand and another man touching and merging into one another, with one living and one dying, and her not being able to tell which is which. He thinks it is LTT, but we have now seen in tGS that LTT is not a real person. He is certainly not going to survive Rand or vice versa.