Leo's so focused on the attacking creatures, he doesn't notice at first that Donnie has joined the fray. His attention is all on what he's doing, beating back anything that tries to get close. He's a blur of motion, frenzied and desperate, taking no care for himself in the face of trying to protect that who is most important to him.

But then he turns and sees Donnie, whacking back another creature with his bo, and his heart leaps into his throat. Another beast leaps from the shadows, making to attack his brother, and Leo yelps and throws himself at Donnie.

His aim is to cover Donnie with his own body. It's fine if he gets hurt, he just can't let it hurt Donnie, please, he can't let his brothers get hurt again...!