Responses
I know that it wouldn't shoot Soma do to him being a useable pawn. Ciel uses people not kill without a reason, and he doesn't have one.
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I know that it wouldn't shoot Soma do to him being a useable pawn. Ciel uses people not kill without a reason, and he doesn't have one.
The gunman is Lizzie.
I say this because, one, Soma knew the gunman. Since Soma greeted them with familiarity.
Secondly, Soma greeted the gunman with the generic pronoun, "you". Soma never greets Ciel with a generic pronoun.
Thirdly, the gunman is likely shorter than Soma. From the panels we see from the gunman's perspective, Soma is bent over to feel the gunman's forehead. Plus, to aim at Soma's forehead the gunman angled their hand upwards.
And some extra things to keep mind, the gunman likely isn't one of Ciel's servants.
With the above in mind, the list of characters that meets the above criteria becomes extremely limited. Off the top of my head, this list includes; Lizzie, Sullivan, possibly Ran-Mao, former classmates from Weston, and Harcourt.
The most likely imo is Lizzie due to (the possible foreshadowing) Ciel and Sebastian briefly muse that something severe has caused a dramatic shift in Lizzie's mindset.
The others from my list is unlikely mainly because Sullivan likely wouldn't jeopardize her current protection to personally kill a person. Ran-Mao uses giant maces to assassinate people. A Weston College student or Harcourt is also unlikely do to not having any direct like to anything related to things that would warrant Phantomhive attention.
This leaves us with Lizzie. The only other plausible alternative that I can think of is "a character we haven't properly met yet, but has been meeting with Soma offscreen".