Before picking specs, I need to ensure feasibility. Only one of the planets need be Earth-like; in fact, I would prefer if the other planet were rather small and dead, like a moon. The orbits will be eccentric enough to produce tectonic strain. Obviously they'll be tidally locked.
What would the tidal bulge on the home world be like? Would the planet take the shape of an egg? Is it reasonable to suppose that an immense volcanic plateau would form in the shadow of the sister world? Might there be major geological uplift?
I'm trying to create this plateau landform within scientific parameters. The only other necessary condition I can think of is the length of day-- it must approximate the 24-hour cycle (though with some room for variability, as a relatively long day/night cycle may also be an interesting feature of this world).
I basically want a normal world that gets weirder and more alien as you near the spot directly below the sister world. I'm thinking that plateau and/or surrounding environs will resemble Iceland's landscape. I imagine leading up to that you'd find a Patagonia-like desert strewn with what seems like a geographically far-flung "staircase" of strike-slip faults, escarpments, and terraces.
Is this scenario plausible, and, if so, under what conditions?