In Chapter 17 & 18 does John's contemplation of death conflict with our impression of his strong character in Brave New World?

I am not sure that I would characterize John as a "strong"
character, although I'm not exactly sure what that means.  John was an "alien" being in
Brave New World; he had a set of values that were in conflict with
almost everything he saw in their society.  His reactions were passionate, but I think
they came from his inability to understand their world and his holding on to what had
made sense for him throughout his life.

Toward the end, he
seems to be overwhelmed by his inability to deal with or change their world, so he opts
for suicide.  I also suspect that this was a "practical" need in the novel.  All the
characters had served their "purpose," so Huxley may have decided to wrap up the lose
ends by having the Savage end his life and just let us imagine that things continued in
BNW has they had "always" been.  In a sense this reenforces the theme that the
individual has little weight in their society, no matter how much Shakespeare he/she
knows.