Filtering for Ike and Soren on ff.net shows 373 works vs 66 for Ike and Elincia. Even when you check the little "pairing" box, it's still 36 marked Ike/Soren vs 8 marked Ike/Elincia. It's crazy, since the big FE pairs have mostly been between Fates/Awakening characters, but after Heroes I see Ike/Soren everywhere now -- looking at the general FE page, it seems like the most popular non-Fateswakening ship period. "Canon" argument aside, I can see how people would see this as a deliberate choice on the part of IS.