When did Soren realize he loved Ike?
I believe with near certainty that Soren did fall in love with Ike almost immediately. However, there is an argument that he might not have realized he did right away, so what are some moments he may have noticed?
There are a few moments that make sense to me:
Before the game even started, during the backstory. This is a very plausible option, considering he searched for years for a person he met once. He has had a lot of time to ruminate that we just never see.
During the Path of Radiance A Support, specifically after Ike reassures him he's fine the way he is. If Soren didn't know before, there's a very good chance he does now, and not just because of the line they censored in the localization, but also because he cuts himself off and then immediately starts giving Ike even more information about himself that wasn't asked about. This also provides the catalyst for Soren to admit to Ike that he only wants to be with him (at least platonically).
I find it highly unlikely that he doesn't know at least by Radiant Dawn, given his blatant wedding vow A support line, his defensive non-denial to Micaiah's "accusation", and his dramatic response to Ike being about to compliment Aimee. Not to mention the line "my only wish was to see you again" which definitely made Ike realize the depths of his feelings, if he didn't earlier.
What I do believe is that he would have a very hard time believing that Ike loves him back, even after Ike realizes he does, and you can sort of see that in the last scene, where Soren's first assumption is that Ike is only trying to hug him out of pity and not because he loves him. And of course, at least before the Path of Radiance A Support, Soren is convinced that this relationship is more precarious than it is. That might also explain why he doesn't want other people to know about his feelings, or try to advance the relationship at any point on his own*, because that could lead to him losing the relationship he already has, which is still more than he could have hoped for.
*In fact, during one of his bond conversations with Alcryst in Engage, he states "If you expect a refusal, don't ask". Now, granted, Engage was written long after Radiant Dawn, so this may not be entirely accurate, but it does seem consistent with what else we know.












