My impression is that in MoR Voldemort was a passionate young revolutionary in the first war, but since then he's gotten older and his outlook has changed. He sees the muggles as the greatest threat now, and he recognizes that his history means he can't take power in his own name without a long and devastating series of wars that would leave the magical world exhausted and vulnerable to this outside threat. So it would be rather convenient if he could sway Harry to his way of thinking and arrange for the wizarding world to unite under a leader who sees him as a mentor...