Rowena was a young girl who lived in Senntisten during the Second Age. At some point, she was eaten by the ChthoniandemonSenecianus, the guilt of doing so making him insane. During Broken Home, Senecianus takes the form of her ghost whilst he dreams of her playing, and it can be seen throughout the mansion.
After the quest, a pet version of her can be obtained by replaying the quest without dying and eating one or less mystery meat. She can be summoned through the follower pets section of the pets interface, and can be stored in a Menagerie. If she is interacted with, she will say "Well, at least it's not haunted here. Oh, wait..."