Yep. I agreed to watch a friend's cat while she was away on vacation. Two weeks. When she dropped the cat off she told me that her cat was very shy. The cat wouldn't come anywhere near me initially, so I just tried to be soothing when I talked to her, and not scare her. This was a weekend, and I was sitting on the far right end of the couch, and the cat jumped up on the left end. We looked at each other, and I again tried to be soothing to her, and then reached my hand out. She immediately took some of my flesh with her and did a number on my arm.
I didn't react, and just figured she needed more time. I went to bed, and left the door open, and then woke up at about 1:00 am, as the cat was rolling her plastic ball around under my bed - on a hardwood floor, bouncing it off the walls. I tried to get her out from under the bed, now at ~1:20am, and again got sliced up.
Finally, I went to sit on the couch, and eventually she came out of the room. I ran back into my bedroom, closed the door, and tried going back to sleep. After falling asleep again I was again awoken - this time by her scratching my door and meowing. So, I opened the door (after putting her plastic ball out of reach) and went back to bed. As I was trying to fall asleep I heard ripping sounds, turned on the light, and saw that she was climbing the drapes and was about four feet off the floor. So, I put several pairs of socks over my hands, up my arms, and took her off the drapes (all the while she was trying to again slice me up). I put her in the bathroom, with the litter box, food, and some toys, and closed the door.
I probably fell back asleep by about 4 am, and had to be up early. When I went into the bathroom the towels had been shredded and were all over the floor, along with the litter. I never lost it with her, but it was a very long two weeks. When my friend got back, I got a nice paperweight as a gift. My conclusion was that cats can be nuts.
What an ordeal. Looks like you never got to the adorable, cuddly and dear side of that cat. So sorry, they really can be wonderful friends. Perhaps your human friend doesn’t know how to train or treat a cat.