Hate to have to bring this up, but... is it really a rivalry if their only interaction is one killing the other in the intro?
Rivarly implies that they clash repeatedly over a period of time. The whole point of C&C:RA is that Hitler isn't actually in it.
I've nominated them anyway, of course.
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"I'm Commander Shepard, and you're standing in the biggest library in Citadel Space. Look me up."