No, they never kissed—in the anime, in the manga, in the video games.
Although, when both were under the influence of Kim’s magic and Spirit’s magic potion in the audio dramas (…long story), Soul was attracted to her, and she was attracted to him. But that was magic, so it is not absolutely clear how they feel for each other and rather problematic to read shipping into those instances.
'Cause it's not like she ever noticed his sex appeal.
In a completely platonic fashion.
While they are getting pummeled by a Venom reject grafted onto the back of a traumatized child, she decides, hey, now’s the best time to dance with her
boyfriend sweetie weapon while they are dressed all fancy after the coward chickened out and left her dancing with her papa. (…Where are you priorities, Maka?)
And they make beautiful music together.
Don’t get me started on the head-touching.
There is also stuff about genderbent, but that’s a long discussion.
And it’s not like their narrative and character development is built in part around Maka facing the idea of infidelity and how she determines to overcome such doubts based on the evidence that she can trust this person, this partner—in body, mind, and soul.
On the one hand, I am annoyed by the need to turn so many opposite sex friendships into romantic or sexual relationships, as I think it limits storytelling options and suggests that the friendship has to be made romantic.
On the other hand, I ship it—I see the evidence, and I appreciate when writers, especially fan writers, draw upon previous chapters in order to make the relationship realistic and contributing something significant to the overall story. I think that almost any relationship can be made romantic with the right writer: it is just a problem of figuring out how to get that story to work without becoming cliche in the worst ways possible.
And of course soma-is-debatably-canon.
Granted, what counts as “canon relationship” is loose when it comes to shipping. Some people want a kiss; some people want “I love you”; some people want hand-holding; some people want graphic detail; some people want the author to break into the comic itself, wave at the audience, and say, “They’re canon, now leave me alone!”
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