Gary's initial reaction was twofold when he found out about Marie. The first one was worrying, wondering if she was okay.
To his mind, for Marie to have turned was only plausible if she was forced into it. Someone must have bit her trying to take control of her.
However, the fact that she was now part of the Pack let Gary wonder what the other person's intentions were by turning Marie.
Because based on his system if Marie was to die now, she would disappear from the list, notifying him immediately.
Which was when the second emotion took over, anger. Anger due to the fact that for whatever reason someone had deliberately risked his friend's life.
It was why he had decided to pick up the phone and call the person most likely to have turned her in. However, Kai revealed not to be the one to have turned her and he knew Midwak was still in Notsburg, leaving only one possible suspect.
"Alright, at least the good news is that Marie was successfully turn-"