You should know your brother enough by know to be aware that he does get attached, and never gets un-attached.

"I won't take lives." This part, he's adamant about. But then he softens, because he can hear oh so clearly the protectiveness that so often took a very strange turn recently, annd he can process that, unlike ... most of his recent encounters with Nai.

"But I won't let myself be caught." This one he is evn more certain about. It sounds liek a promise.