Alright here's some difference with Rahzun while he's in Dark Killers and Midnight Lore
While in Dark Killers he has the habit of possessing humans making them do whatever they want as he please and he is shown to be sly asshole not giving a shit
In Midnight Lore he still acts the same though he tends to tone it down a little but he'll possess people when he wants to just to mess with Evangeline and sometimes Treznor and is still sly also loves to mess with a certain spirit *wink wink nudge nudge* but he'll help out if Evangeline needs something
He's kind of Evangeline's ally he doesn't hang out with her or Evan's friends that much and does has the habit of coming out of nowhere
Also he doesn't really calls Evangeline by her full name or anyone he just gives them nicknames
Evangeline: Dhampy/ Little Hybrid/ Dhampir/ Clumsy girl/ child
Treznor: Mutt/ Wolf/ Doggie/ Wet dog
Yeah Rahzun wont change at all
