My worst experience was mobbing with someone who hated the idea of mobbing (or pairing).
In one of the early mobbing sessions, probably our first without an external facilitator, one session was particularly painful. After all the work I put in to convince the programmers to practice together in the name of learning for two hours, one of them felt forced into it.
Well, he felt forced into pretty much anything. Over the course of 4,5 years with the team, he labeled me as "organizational cancer" - whatever I was doing was destroying whatever he felt was important. He told me I existed to "ruin the life of introverted developers" and other even meaner things I endured on a weekly basis. But one amongst 10 really wonderful people can be dismissed, even if it definitely can wear one out.
But he was one of us, and we wanted him included. So he was, in particular from the invite from the manager insisting we'd do learning together as a whole team.
The mobbing experience that followed was 1,5 hours of agony. There was a consistent flow of negativity. We got to hear how this group work thing is like being in kindergarten. How adults should stop playing at work. We heard in various ways how much he hated every moment of it. When driving, he refused to play by the agreed rules of letting thinking happen outside the keyboard, and just went into coding with an audience, not even explaining. Everyone was in pain, yet none of us said anything at first, just trying to get the work done. At the end of the session, I was exhausted, and so were everyone else.
My frustration finally came out as a remark telling the guy that this thing in life isn't compulsory. If he hates this so much, he is welcome to drop out from the next sessions we had scheduled. His face lit up, with "really?" and he looked absolutely delighted. The others said nothing again, until only two of my team remained, including the manager. They pointed out that leaving him out was bad because he would need the learning mobbing could give the most. But we went with letting him opt-out.
The rest of the team mobbing without him had a great time. We learned a lot, we got things done, we developed empathy towards each other. And every time we showed up from our mobbing cave, it was like we had just been in a great party. He was invited, but opted-out.
Until one day he said he could join in. The fun others are having is inviting. We told him he is welcome, but the behavior we endured once wasn't going to be ok anymore. So he joined on occasion, observing and navigating, still opting out from the driver seat.
My lesson learned: you're better off without someone who hates it. And that the fun, party-like feeling of mobbing you're excluded from might just be a thing to draw you in. So allow opt-out, either completely or partially. Even make that explicit. We did not force him in the first place, but he felt it was compulsory as a whole team activity.