Not sure I can narrow it down to one person, but I absolutely love it when (as has happened many times over) I get to know an elderly person, and months, or often years into knowing them, (ir even, sadly, at their funerals sometimes), you start to find out about things they've done in their life that are really eye opening.
I think it can be too easy to take people at face value, and 'as they are now', and, despite it happening many, many times in my life, it is easy to forget that they were once 19 or 23 or 36 or whatever, and that probably are still that person inside.
I think the first time this happened was when a great Aunt of mine came home from Australia, where she'd lived until she retired, so I obviously didn't know her, and I found out that she'd volunteered at the start of the war, and had nursed in the army in Africa. I often think of her if I watch a film or TV series, about that time, or read a novel set in war time, and you think about these young women who went into the unknown. After the war, she had 'wonderlust' and went to live in Australia, which, at the end of the 1940s, meant she never saw her Dad again, and only travelled home once in that time when she saw her siblings and Mum. It just seems such a different life from me meeting this grey haired lady, back when I was a child.