In Chapter 129, there is a scene showing Nagi and the other members of the Crimson Wing. In front of Nagi, there is a member of the Crimson Wing who does not appear in the photograph which Negi has. This new member seems to to a young Mage since the new member is definately wearing a Mage cloak like Nagi.
This young mage can't be Alberio because he is shown outside the scene. The young mage can either be a young Fate or Negi's mother. If the young Mage turns out to be a girl, we have our first clue of Negi's mother. Negi's mother would have to be a tomboy, in order to be a member of the Crimson Wing.
At the present time, the true identity of the mystery member of the Crimson Wing is unknown. So far, all I can state that the mystery member is a young Mage.
:hkss: