I have an indoor male cat and he has always been a nice cat, never intentionally causing proper harm and always gentle when playing. A few scratches here and there but that's all. More recently though there's been a few times where he's been quite aggressive. I will list a few examples of how this has happened and how he reacts.
About a month ago he kept trying to jump onto the counters when food was being made and being lifted off them constantly as he wasn't allowed up. He was going to jump again and my sister stopped him, he then must've scratched her so she dropped him, then he ran to my mum's foot and clawed it up badly. All his fur was standing up and his tail was huge and he was meowing loudly and weirdly, my mum didn't scream at him to try not to make it worse, offered him treats and closed him in the bathroom until he calmed down.
Another time was recently when I came home from a friend's house (who has a cat), just outside my door was another cat, I petted it before going in, and then petted my cat who was sniffing my hand, then his fur stood up and he did his meowing again. Everyone ran away in fear because that's his "attack mode" but I stayed and just spoke nicely and got him some ham until he calmed down then he was fine.
And a few days ago he attacked badly again, he managed to get outside as the door was open and as soon as he was out he puffed up, but he was fine when my dad called him over and petted him, but apparently my brother grabbed him with a towel and put him back in the house and then he started meowing loudly again, and attacked my dad's arm.
It's happened other times where he puffed up and meowed but not attacked. I just don't know understand whats causing this and how to solve it. My parents are talking about getting rid of him because of it but I'm trying to prevent that because he's a great cat every other time.
He isn't neutered but I am planning on just getting all necessary things done for him asap even though it will be costly. Would neutering (if that's the word) help calm him down a bit? And is there anything else that could be causing this random aggression?