If I had to make a guess myself as to which Temple Guard was the future Grand Inquisitor, I'd have picked this guy. Zero compassion. He just approaches Ahsoka from behind while she's in shock and yoinks her padawan braid clean off without a warning. Ouch!

On the other hand, this guard here is my fave. He's the only one to bodily come between a lightsaber fight to shield the younglings.

(A different topic is the survival instincts of said younglings and their elderly instructor, who does eventually also stand in front of them. But no one thinks to shuffle over somewhere safe where they wouldn't have front row seats to an actual deadly lightsaber battle featuring a person who has already killed Jedi. Okay, Barriss probably wouldn't harm the kids purposefully, but still.)