Why is Tommy Ricardo so afraid of Pinaco?


In chapter 19 of _Full Metal Alchemist_ , Winry asks Tommy for an
apprenticeship after delivering the baby. As she is asking for it, she
mentions Pinaco is her grandmother and Tommy becomes extremely vexed and says,
"I don't want to remember those painful memories!"

> ![Tommy being afraid of Pinaco](https://i.stack.imgur.com/HIXG4l.png)

Why was he so afraid of Pinaco?

