Freaking fight me with this one but I'm 100% sure Soul is an Aquarius.

Proof ?

-He gets along with Maka so much---and as I said recently, Maka is a Virgo. Virgo and Aquarius are very compatible.

-Soul puts up this cool guy aura so he pretends to not really like Maka---"She has tiny t*ts" as his excuse---but he cares so much about her to the point where he'd catch a bullet with his fucking head to save her. An Aquarius trait. (My father's an Aquarius so...)

-He is mysterious. To be fair, I don't think Soul ever mentioned his family to Maka. He plays such dark melodies with his piano, and I'm guessing they're all made with his feelings.

-He's a gamer. No need to explain, huh ?

-He finds the easiest way out, like what my Aquarius friends do (mostly). Like in that exam episode---he had the time to freaking scribble on each of his clothes just to cheat that exam. Another would be at the first episode, where Maka was saying "We have to be careful and plan ahead" but then Soul went like "Fuck that" and jumped straight in... Both procedures failed, but I'm proving my point, right ?

-He's hot with or without freaking effort.

...Yeah, so that would be it. :P Just a random thought @-@ I'm still sure he's an Aquarius though :P