TL;DR: Question title. (What is a fair way to punish a sibling who unintentionally erases another's Saved Game?)
So this question could (should?) perhaps be posted on Parenting, but I thought users here might have some personal experience with this.
I recall two incidents from my childhood where I erased my younger brother's saved games, both times unintentionally (in my mind).
The first time was when I somehow deleted all the files for SimTown. Game files, saved games, and all. We re-installed the game, but no saves to be found. My brother was devastated and demanded my Roller Coaster Tycoon files be erased in retribution. My parents did not think that erasing save files for a game I'd played many more hours on was fair.
Fast forward a couple years and we're at daycare beefing up the kids starting lineups with the 3 starter Pokemon for Red and Blue. I was the cool kid with the link cable that let us trade, and I volunteered to get everyone set. Not even considering that there is only one save file and that to make a trade you need to save, I overwrote my brother's 100+ Pokedex to trade a Charmander for a Rattata. This horrific act again resulted in no punishment for me, but I did offer to help my brother with a new game.
Looking back, I got off easy. I would have been pretty vengeful if I had been my little brother, and maybe that's why we aren't close today (or because he lives a couple hundred miles away) and he's not the gamer type.
Still, that leaves me wondering what an appropriate punishment would have been? Is erasing the saves of the offending sibling really making things "fair?"
What would be an appropriate punishment these days?
EDIT: Just to clarify, both of these cases were unintentional. The first one due to not understanding how to properly use a computer at the age of 8, the second time just forgetting (and not reading the warning message) that you have to erase the saved game to do the trade.