How you file a TOS violation report like this...

[Jojoya]

I've reported the person stealing my character's name and identity. I feel the GMs did something because now I can't even talk or go anywhere without seeing the same (from above, Third Party insults. I've blacklisted several of them, even found which FC it was in after some investigation. What do I do? Do I write reports of all the times I speak, and right after tell the GMs what these other people are saying. This is kinda spooky seeing this after 5 months after the incident. I just want to play FF14 and help people where I can and not have these weird people saying the same things after every time I speak.

There's no such thing as stealing your character's name and identity. You don't own them.

The GMs aren't going to do anything other than enforce any ToS violations. You're getting a bit paranoid if you're trying to assign blame to the GMs for anything that is happening.

There's no rule against someone else repeating things you say. If they're copying your style and not your brother's, it sounds a lot like their problem is with you and not him.

Blacklisting the player will block everything the other player says from your chat. Sounds like you haven't blacklisted them as you claim.

If the other players are truly trolling over you because things your brother did, the best thing to do is not react. Ignore them. IF they don't get a response, they'll get bored and go do other things.

If they cross the line and do things that actually break the TOS, report that. Stop reporting the stuff that isn't against the TOS (like "copying my look and style"). The more you open tickets for petty reasons, the less likely GMs will do anything other than go "omg not this player again, into the round file it goes". Then when you have a genuine problem that does need their assistance, you're going to have a harder time getting help.

If they're bothering you that much, your best bet is to transfer to a different data center to break the connection. Your peace of mind is worth far more than the cost of the transfer fee. If you have friends on your current world that you wish to play with, you can create a new character instead. It's easy to level new characters once you know the game and you can always transfer gil from your current character to help the new one get some of the things you'd like it to have.