Robot Adept, like much of Piers Anthony's work, is probably best for younger readers, say teenage or so. I can enjoy them as an adult, but I liked them better when I was younger.

Proton and Phaze are alternate worlds. Mach (a robot) and Bane (human) are alternates of each other, and an imbalance between the two worlds is building. Phaze is magical, while Proton works on science.

A part of the trouble is because Mach and Bane have each fallen in love with a woman from the other side. They have the ability to trade bodies, but this is a part of the imbalance that threatens to destroy both frames.

But there are also different forces wanting to control the frames. Mach and Bane are forced to compete to decide which side will rule. The competitions are challenging, with control of both worlds, not to mention the fate of their children, riding in the balance.