katherin,the shadow is part of jack,if one dies than part of the other does as well.it would be like ripping someones soul in half,but sometimes the shadow tries and escapes;as long as jack dosent lose his cool and his anger dosent get to him:the shadow will stay caged,for example:suppose max was killed right before jacks eyes,he would be powerless to stop the shadow from "waking up".also jack could use the shadow to his advantage:he could replace his arm with the shadows arm and not go into a frenzy,if your still confused tell me :3