CHAPDISC: DH33, The Prince's Tale

[lizzyben04]

No: HPFGUIDX 184826

Pippin:
<snip>
Perhaps having a captive audience in his classes helped him gain
confidence. It might be that in earlier years, he relied even more on
the blackboard --perhaps to the good fortune of those who would
otherwise have been verbally scorched.

lizzyben:

I also vote for teaching as making the difference. When you're forced 
in front of a crowd of teenagers, it is sink or swim in a big way. Kids 
will test a teacher, especially one as young as Snape was, to try to 
see how far they can go. And the new teacher can adopt one of three 
strategies: run away crying, explode with rage, or adopt a commanding 
persona. I can see Snape doing both before finally adopting a persona 
that allows him to control the classroom. 

IMO Snape's persona is to a large extent an act lifted from authority 
figures in his own life - it's 70% Lucius Malfoy, 20% Tobias Snape & 
that extra 20% of pure Snape neurosis.