Serena Kitsune is the genetic daughter of Renamon (Digimon Tamers) and Batman/Bruce Wayne (The Dark Knight Saga version). Rey Nar Normandy and Kyto could technically count as her half-siblings on her mother's side.
Not much is known, but she is the creation of Dr. Von Richter (from Cybersix). He somehow acquired the DNA of Bruce Wayne and managed to create a digital field to acquire the false proteins and genetic structure of Renamon. However, combining the two different DNA structures proved to be a bad idea. She was created to fight Cybersix, but after waking up to her ballistic state, she escaped the laboratory and the country of Venezuela to the United States.
After killing a couple who had kidnapped and imprisoned children in cages (and stealing their money and freeing the children in the process), she felt a great amount of pleasure out of helping the children, but she felt guilty over killing people. She didn't understand why, but since then she has decided to help those who are in trouble and kill anyone to scare criminals, child molesters and murderers in order to get them to think twice and turn themselves in. She doesn't consider herself a crime fighter; she knows she's a vigilante and is proud to be one.
In regards to her relationship with her parents, she wants nothing to do with them. She accuses them of allowing herself to be a creation of war and resents them (which would ultimately lead to a fight with Rey or Kyto).
Serena has promised Konrad, Kimiko, Faeton and Anurto that she wouldn't let anything bad happen to them, but other than that, she really doesn't seem to like any of them, and it seems the same way with a lot of them. She already dislikes Susan after she found out that she was the one who gave Dorian an alcoholic drink and started beating her up for it afterwards, much to Dorian's dislike since he said that he was the only one who should beat on Susan. She also threatened to kill Piper, though why that is hasn't really been explained very well since all she did was ask who she was, which has already made both Piper and Dusk dislike her.
Serena seems to be mentally unstable. She is quickly prone to anger at the slightest of annoyances to her, and, should whatever it is get on her nerves, it would get mauled. At times she can act civilized, but other times she can act like a wild animal as evidenced by her murders. However, she mostly acts like a moody teenager. This is due to the fact that during her development stages, her physical and mental growth stopped around the perceived age of seventeen. As a result, she can be moody and aggressive at any time, but she can be curious at others. If she comes across situation she originally had no part of, she'll get herself involved regardless and start demanding answers.