Over the course of the first season of The Blacklist, we see Reddington looking for clues about a girl whom we may assume to be his daughter. Most notably, we see him remove one photograph from the book of victims of the Stewmaker (S1E4). Berlin turns out to have the same photograph in his pocket watch.
But in the season one finale, only then Reddington seems to learn that Berlin is after Red for what he supposedly did to Berlin's daughter. It seems as if Reddington has no idea about Berlin nor his daughter before that.
So why was he looking for her?