intro
If you first met kiyoko before The Accident, you could say that she was polite, reserved and seemed like she wants nothing but to sprint in the other direction.
However, if you met her in the apocalypse, presently, she would probably try to kill you and eat you. (and most likely succeed)
Nothing personal. Dragon's gotta eat.
kiyoko is decisive, skilled and cunning.
that is, until she met leto.
When Kiyoko realised Leto actually had a will to live, a goal to achieve and that she would've gone any route to achieve said goal, Kiyoko didn't really feel like eating her anymore.
instead, Kiyoko gave her the way out
instead of leaving, however, Leto stayed by her.