Board Thread:Speculation House/@comment-3146930-20140708014442/@comment-3146930-20140718192032

In the final episode of Volume 1, Blake mentions that she no longer wanted to use her skills for violence and would dedicate her life to becoming a Hunter. As mentioned from a few different episodes, what a Hunter does is protect the peace, so Blake is dedicating her life to helping people (not just humans specifically, but aiding people against danger).

As far as Blake being more open with Sun, sometimes a perfect stranger is easier to talk to then someone you know. Also I don't think they were living together for half a year; the only kind of time table we have from the time they enter Beacon to the time the final episode air is Glynda mentioning that it has been several weeks (in relation to Jaune's lack of improvement). At most that is like a month and a half and if Blake is trying to prevent anyone from knowing about her past, she may have constantly kept an emotional distance from them. It would also make sense for Ruby and Yang to be calm because Yang is openly friendly with everyone and Ruby seems like she would want to keep the only friends she has, considering her lack of friend making ability.