You had successfully defeated the octoling responsible for this mess, Tartar! But, as a result, you learned the sanitization goo was actually sentient and needs a master who isn’t infected to lead those infected. And it turns out, the goo considered Tartar its master, until you beat him. Soon, you find Agent 3 sitting on her knees in-front of you.

“I serve you… Alpha.“

She stood, and held her hand out for you to take it. She’d happily teach you how to lead the infected as their Alpha.