No, it's not all there. That Khan had a wife is there. That he blames Kirk for her death is there. But who she was, how she became his wife, what she actually meant to him, is not there. It's only in Space Seed. Khan is crazed in TWOK, but that can be easily attributed to the conditions on Ceti Alpha V. Only those that have seen Space Seed know just how much of it can be attributed to who Marla McGivers was, both as herself, and to Khan. What's unfortunate is that Madlyn Rhue was asked to do TWOK, and refused. She didn't want the world to see her suffering from MS, and had backed away from acting at the time. Yet, if she'd done the film, no one would have ever known, as her part would have been exclusively lying in bed doing a poignant death scene with Ricardo Montalban. If she'd done the scene, Khan would have been a much more tragic figure, rather than the mere madman we saw.