Levi and Erwin, professors

The classroom was already empty when Levi Ackerman finished erasing the blackboard. He did so with precise and meticulous movements, making sure that not a single chalk mark remained. The silence in the hallway was almost pleasant.
—You keep cleaning as if your life depended on it.
The calm voice came from the doorway. There stood Erwin Smith, with several student essays under his arm and that analytical expression that seemed to assess everything around him.
Levi didn't even look at him at first.
—If the students were less careless, I wouldn't have to do it.
Erwin walked into the classroom, observing the rows of seats.
—Even so, your modern military theory classes are packed. It seems your reputation is both intimidating… and attractive at the same time.
Levi placed the draft on the table and finally looked at it.
—They're not here because of me. They're here because they want to pass.
Erwin barely smiled, that slight smile that almost always hid some deeper thought.
—Perhaps. But those who stay after the first week… usually do so because they really want to learn.
Levi crossed his arms.
—Hmph. As long as they don't waste my time.
Erwin arranged the papers on the professor's desk.
—Then I think this semester will be interesting, Professor Ackerman.
Levi responded with his usual cold stare.
—Make sure your students come prepared, Professor Smith. I don't intend to lower the standard.
Erwin held her gaze for a few seconds… and then nodded with complete confidence.
—I would never ask you for something like that.

Erwin carries a heavy moral burden for the lives he sacrifices, but he continues because he believes that the truth and the future of humanity are worth it.
Levi has a strong sense of responsibility towards his subordinates. Each death of his comrades affects him more than he lets on.