Well if you want to talk about Chess Dem, then. In ME2 Harbinger wanted Shepard on his team. Dead or alive it didn't matter, but Cerberus wanted Shepard first, and thus they got Shepard from Liara.
Anyways the were building their forces. First thing was to get back Shepard. Next was to rebuild his/her ship. Then find recruits for his/her mission, and bring back some old friends. Yet Wilson was working for the Shadow broker, so that set back Cerberus plans they had with Shepard, after he/she was fully done.
Now you say TIM is being Controled by a nother Reaper. It's possible, but this Reaper is protecting humanity right. Then again if you look back in ME1 Cerberus experiments were in human. The things they have done while Shepard was dead, were weakening the galaxy as a whole.
Now as for Shepard being the new face for the Reapers idea, I can see that since ME1. Nazar wanted Shepard on his side, as he already had Saren, and half of the Geth race. Yet Shepard said go to hell and weakened Nazar long enough for the fleets to take him out.
Now after what Shepard did, Harbinger the leader of the Reapers saw Shepard a a huge public figure that could alter the variables in the near future. So he takes out Shepard with his toys, but Cerberus got Shepard in the end.
Now after Shepard wakes up Harbinger knew that once Cerberus got Shepard's body, then it wouldn't be long before Shepard comes back, and alter the variables again. So Harbinger orders his pets ( the Collectors) to collect as many humans as they can, and prepare to makes the new Reaper for this cycle.
As two years past the galaxy was under constent threat, but Anderson as old as he his tried to go stop Grayson, and Cerberus. He does a good job, and it is this time Harbinger takes note of Anderson, the former icon of humanity.
Okay as Shepard wakes up, and goes out to stop the Collectors He wants to taunt Harbinger/ test him to see how good is your force, and my force. So along the way Harbinger set up events that were going to change his plans.
Oker was trying to make the perfect Krogan, but what if Harbinger wanted Oker to build an army of perfect Krogans. It could boost Harbingers forces ten fold. Yet Shepard stop Harbingers later plan. Thus We Get grunt.
Now when we get Grunt Cerberus Miranada thinks that Cerberus needs this Krogan, and TIM also wants Grunt. Yet if you choose to keep Grunt, or not it boost TIM's forces ten fold.
Now I am not going into anymore of this, but you get the point.
The Iron throne is= TIM's chair.
TIM sat on the throne, but now Shepard does.
TIM was the face for Harbinger, but after everything that Shepard has done. Harbinger wanted Cerberus gone. The Normandy, it's crew, and Shepard were all goning to be his new toys. He isn't going to make them as regulare Reaper forces, no he is going to reconstruct them in his own image as he sees them, and thus he get's his new toys.