I think the real question is, why would they like each other (at first)?

Assuming we're talking about like due to socionics factors, there's no reason to think someone you don't yet know has any redeeming qualities which would allow you to form a good relationship. If you've been in a rewarding dual relationship before, it might be easier to identify how beneficial a dual is to you, but even then it's not a given. I like Gulenko's explanation in the video below of how duality works.



Note that he says a few things which run against common conceptions:

-Duality has to be spontaneous, not planned.
-Duals may find each other irritating at first
-Your dual has to be able to provide help with some problem you are currently having. Note the example of the SLE "rescuing" the IEI in the scenario they act out.
@Adam Strange this may interest you