Since your TLM priest brought this up , it would be best to take it back to him to answer your questions.
There are many examples in the Church, but you have to be careful, as there are a few possibly false so called victim souls. Again be advised by you priest.
I believe there is no dogmatic teaching by the Church, but there are some assured victims, like St Paul.
A victim soul is one who is given extraordinary suffering for the sake of others, over and above our expected human suffering, which I believe is God’s way of pulling us into line and illustrating our total dependence on Him.