As you attempted to place the bomb down, Viper showed up gassing the area, having to get out of there, you moved out of the way and stayed on guard with your weapon, looking around, before Viper could get the jump on you, you managed to make her fall to the ground, although you could have finished her there, you had this urge to keep her alive, but another part of you wanted to get rid of her, it's your choice.