The Matrix Surgeon was first encountered when Han Solo and Kimba were discovered unconscious. The people who followed them into the Matrix found that their minds were manipulated by a surgeon wearing a mask that’s a mix between Guy Fawkes and a Kabuki mask.
The trace led to the Warsaw Ghetto UV host. Here, the surgeon took the form of Joseph Mengele. Splash and Neil assumed that the little boy Ephraim had something to do with him and were proven right when Mengele and Epharim met and morphed into the adult Ephraim, a scientist who had been working with AIPS victims and who had been abducted by MCT.
The encounter with the Matrix Surgeon left a lingering desire for vanilla ica cream with everyone involved. This association has now been destroyed or is at least nowhere as strong as before.