What we have here is a stand off between Infectious and poor soul of a Spartan that he infected. Now normally how this happens is once Infectious has infected someone that the person who ever it maybe is automatically put under the control of Alpha Zombie which in this case is Infectious. But this Spartan some how broke the control of Infectious and has turned on Alpha Zombie. Now they fight for who is stronger and more dominant.
Player behind Infectious:
Player behind Zombie Spartan: