Someone Collides With Rachel and Brad

It was when Rachel was leading Brad down the hall that they accidentally collided into someone exiting the stairwell. All three of them collapsed to the floor in an undignified pile.

A second later, the person they bumped into pressed his (or her) hands against Brad's bare chest, to help himself (or herself) up, not realizing that the branding was now on one of the person's hands.

But who was it that now bore the newest branding?