What's the worst thing a sibling or inlaw has done to you?

This was an in-law: travelled to attend our wedding, asked me to a cash a check (due to direct deposit pay check supposedly going into the bank during travelling time), and the check I cashed bounced. Unbeknownst to me, the cash I handed over was fully spent during the visit (including on things like buying souvenirs for coworkers) and, about a week later, I got the notice from the bank that the check had bounced. I was out almost $800 plus the $25 the bank charged me for the NSF check. In spite of promises and other action, I was never repaid (in four years) and now that particular in-law just completely avoids contact in order, I assume, not to be asked for the money. Wasn't a very nice situation, I tell ya.