literally all i know about frank castle is what i have gleaned from...this kinkmeme, so it boils down to: a) likes matt a lot, b) murders just shitloads of people, c) gets protective/flirty bout matt (STILL NOT OVER THE ALTARBOY/CHOIRBOY WHAT) so i can only imagine that at first he's like "wtf who are these people kidnapping you lemme at 'em i will MURDER THEM TO DEATH FOR YOU"