Stella is a creature from the Void. It is unknown if she even has higher thought processes. She does kill many people and no one knows why. That is to say, it's obvious when she's fond of someone. She often leans against them and will follow them. It's not clear what kind of people she likes.
She takes organs from her victims, but no one knows what she does with them. Other inhabitants in the void will bring her organs and whisper her name as they hunt.