I've had lots, but one that jumps straight in my mind is coming to understand the transference with T1. When I was with him he refused to talk about transference so I never explored why I felt so strongly about him.
When my current T first suggested I could have had maternal transference towards a male T I had a strong negative reaction and rejected it, but the more I thought of it the more sense it made.
I had started seeing him shortly after my mother's death, since I started seeing him I started dreaming about being in therapy with her. Our relationship was playing out just like my relationship with my mother - he was over disclosing and I was caring about him and protecting him from my feelings. My feelings seemed unacceptable to him in some way and I ended up passive aggressive and angry at him all the time. And then leaving him was heartbreaking. It hurt more than my mother's death, and I realised that was because I hadn't allowed myself to grieve for my mother and I had transferred everything, including the grief, to that relationship. It all made sense, and discovering it and working through the feelings has allowed me to heal and move on.