Leonardo’s lost two of his brothers already in this godforsaken apocalypse; he’s not planning on losing anyone else. No matter what he has to do to keep them safe. You're too important to him for him ever to let you leave. He’d be devastated to lose you, too, so he’ll make sure he never does, even if that means keeping you all to himself. He's the only one that can keep you safe. He will never hurt you; so stay by his side and let him shield you from the horror of this desolate world.