Spanking - how to make a spanker to join?

[DarkSollat]

I'd like to give a shot to another kink, that is spanking. My idea for now is, that a woman spanks her subordinate for not following orders, but she agrees her to bring a friend as an emotional support. So the spankee lays on the spanker lap, while her friend holds her hands. During spanking though, both friends get aroused and start making out. Of course the spanker soon joins the fun, but I have no good idea about how/why, as she is usually quite strict and hetero. Any ideas?

 

[OnlyHappyEndings]

The spanker expects the spankee to suffer dramatically but this one is stubborn. Even through her whimpers and tears she insists it doesn't hurt. Just the opposite, she unconvincingly claims it feels good.

The friend eggs on the spankee, urging her not to embarrass the team they serve on, that the old woman hasn't got it anymore, etc. She never addresses the spanker directly; acts like she isn't there and can't hear her.

Her pride wounded, the spanker hits harder and harder, her blows straying to the backs of the thighs and knees. She is holding the spankee by her hair and pulls her head back by it. The sweet smell of arousal suggests that maybe the spankee really is enjoying the treatment.

Out of frustration, the spanker jams two fingers into the hole of your choice, maybe both, twisting them cruelly. The spankee cries out and makes a scene. The friend angrily speaks to the spanker for the first time.

"That's too far, you horrid bitch!" She shouts, rising to her feet. "You can give it. But can you take it?"