To wonder why someone would do this ?

[PinkRiceKrispies]

Go back to a workplace where they felt bullied for a visit and spend ages there voluntarily, chatting away happily to all the people they were complaining about (and crying over) previously? They have another job now too.

To show their bullies that they have moved past their awful experience?

Sounds like a good bit of closure.

She told them she dislikes her new job so wasn't a look at me, I thrived without you all kind of thing.