After dinner, just about ten minutes before he would transform, Eddie went to check on the werewolf. He planned to stay a good portion of the night because he does have experience dealing with werewolves who haven't been taking the Wolfsbane potion. He went at some point not long after it transformed to use the bathroom. When he comes back, whoever's been to help the guy escape has done their thing.
So it escapes, and Eddie immediately goes into battle mode, so he's sending off stunning spells and other sorts of hexes and curses that at this point are meant to disable and not kill. Feel free to have someone catch a stray one of these spells! They won't be hurt for long, and nothing that will lead to a permanent injury - no Sectum Sempra!
... yet. Before Asala can do her thing and kill it whereever it ends up, Eddie starts throwing that one around, and cuts the werewolf a few times badly, but it doesn't die.
He's beaten up pretty badly when it's all over, and I am so more than willing to have the werewolf actually trying to go after him when Asala kills it. Like, Eddie is trapped under it barely fending it off oh god he's going to die.