Well said. I don't have any problem with that kind of character or story but I don't think there's anything remotely close to supporting it as canon, and that includes the ending with Soren. You have to take into account everything about Soren's character, the history he has had with Ike, and how that relationship grew out of his first encounter with Ike as a starving outcast child. I didn't see anything more than two very close friends, one of whom basically owes his entire existence to the other and has to balance that against an incredible amount of justified anger at the outside world.
Perfectly legit to interpret it however you want though. Wouldn't at all change my opinion of the character if some content were introduced that did make some kind of other relationship canon; I just do not see it at all in what we have so far.