Yeah... I don't think Darkblue did accidentally show us Steve in this shopping mall... Steve was there for a reason... And the Emma's picture was taken there... So... It's an accident he was there, he has an own agenda, he works with fake Wainstein, Jason (or dirty cops) or he's on MC's side and watch his six...
Personally I think that was a red herring. it was perfect timing, MC sees Steve being weird in the mall, then later that night the house gets broken into by someone who took a picture of them right as we saw Steve. it seems too obvious.
I have no doubts he has his own agenda, but it probably isn't malicious, I hope
My theory is that if you are on the Charlotte path, then at some point you will be able to have Steve and Lucy meet and hit it off.