Originally Posted by Vengeance
There's a chance that he foolishly gave himself Titan power during the assault to try and protect the town and his family but for whatever reason couldn't properly control it. Instead of protecting his family he ends up killing his wife. I think it could very well be possible. It'll explain why he's been missing after giving Eran power. He left to protect humanity from himself since he has little-no control over his Titans actions. Smiley is the one who attacked their house and Smiley just so happens to show face now of all times. Smiley can't be just another Titan at this point seeing as he's been given importance by showing face again.
I'm hoping that Smiley is delved into a lot more in the next chapter. I'm not reading too much into this now, because we have a good handful of characters that should be the core group. But all I really foresee is Smiley's death... that, or Eren gets eaten and sees his head or something like that.