AE lock isn't linked to anything - it locks whatever metering is set, however it's set, until the shot is taken (or enough time passes, 16 s as default, IIRC).
Of the four metering modes (evaluative, center-weighted, partial, and spot), evaluative is weighted toward the selected AF points on both cameras, center-weighted and partial are centered, but spot metering differs - it's fixed in the center on the 5DIII, but linked to the AF point on the 1D X.
