Disclaimer: I don't own Buffy the Vampire Slayer.
Kendra did not want to die.
She used to be the good Slayer, the one who obeyed the rules and the Watchers, the Yin to Buffy's Yang. She didn't think about such things as when she would die, or who would kill her, she only thought of the Hunt - the keen thrill in her veins after a successful kill, and the burn of frustration when she missed. The only thoughts she had of death were the nagging sensation that her luck would run out sooner or later. Kendra made up for this by leveling nest after nest of vampires, struggling to decrease their populations as much as she could before her time was up.
When she came to Sunnydale, she expected the demons and the vampires and the victims. She didn't expect another Slayer, someone who managed to thrive despite their shared calling. She didn't expect someone who embodied everything Kendra had been told a Slayer wasn't. She didn't expect someone who was better at it than herself.
But that's what she got - a smartass Slayer with friends and family, who went to school and talked to normal people and loved a vampire.
That last part was the hardest bit to deal with. Not only did Buffy have to choose a vampire to fall in love with, she had to choose Angelus. He was a member of the Scourge of Europe, the stuff demons have nightmares about. Buffy might believe he'd changed, but Kendra would always keep a wary eye on him.
And what really got her was that Buffy was, despite her flaws, better than Kendra. Buffy had friends and family and love; Kendra got a book of rules and a grouchy old man. It didn't seem fair. Sometimes, Kendra felt like she was the little sister constantly being outshone by her older sibling; sometimes she felt like cheap copper in the shadow of blazing gold Buffy.