student!Snape keeping Lupin's secret (was Re: Sirius as a dog)

[Carol]

No: HPFGUIDX 181293

Catlady wrote: <snip> The famous statement, 'In recent years, only
those whom I could not save', suggests he first developed empathy (or
a moral principle with the same result) 'in recent years', well after
his student and even his Death Eater days. I wish I knew whether it
was empathy, moral principle, both, or neither (i.e. just obeying DD).
> <snip>

Carol responds:

I don't think it's simply obeying Dumbledore, since DD is the one who
asks him "How many men and women have you watched die, Severus?" to
which Snape replies, "Lately, only those whom I dould not save." The
words occur after snape has trapped the ring curse in DD's hand, but
before he saves Katie Bell or Draco. I think the decision to save
people was Snape's own, just as his decision to risk his cover to save
Lupin, against orders to "act [his] part convincingly" in the chase,
is his own (DH Am. ed. 688). Which leaves us with moral principle or
emapthy, take your choice. Snape speaks the words in the summer
between HBP and OoP, so I'm guessing that "lately" means "since the
Dark Lord returned" approximately a year before. Sending the Order to
the MoM might stem from the same motive; even though he would not
actually seen the kids die, he still wanted to save them all, not just
Harry, whom he had promised DD to protect. Or it could go back even
farther, to PoA when he conjures the stretchers or even SS/PS, when he
saves Harry from Quirrell. Once he did that, he may have decided that
he preferred saving people to watching them die, as would have
happened if, like everyone else in the Quidditch stadium, he had not
countered Quirrell's curse.

Carol, seeing another common trait shared by Snape and Harry, a
"saving people thing"