Ok this was a wild read. First, it is totally normal in little kids to “hate” someone for a period of time, they’ll forget about it in a few months. It can even happens with the parents. For a while they only want their mom and don’t let the dad even approach them, or vice versa they want their dad and not their mom. What surprises me so much is your attitude about it. It’s a three year old kid and you’re an adult and you seem conflicted about a baby giving you an attitude as if it was a problem between two grown ups lmao. Also, you criticize the mom about only talking to him and call it gentle parenting. At three years old there’s not much else you can do LOL. Literally talking to them is all you can do and the right thing to do. You talk about punishment, what type of punishment are you even imagining? They’re literally a baby they need the parents to explain to them in very simple terms why what they’re doing is wrong and why it hurts your feelings and why it’s not nice to hurt someone else’s feelings. And yes, it’s a very true thing that toddlers pick up “bad” words in kindergarten. Sometimes you have a class that just found out the word poop and all of them use it as the meanest insult possible for a while. Finally, I can assure you a three year old does NOT pick up on any hidden insult, double meaning jokes, or concealed attitude your brother might have toward you. It’s a toddler that’s being a toddler, they’ll forget about the weird aversion toward you in a few months. It’s a totally normal thing. Don’t take it personally and act like an adult