Standard human fighter

A character that compulsively fights every human they meet is a great way to frustrate a DM with chaos.
- Player: why do I feel that the entire universe is turning against me? All I wanted to do was kill literally everyone.
  
  My DM once gave me a cursed sword that required me to kill a humanoid daily.
  It then devolved into side bars where we had to negotiate taking a kingdom's prisoners with us in the hold of a boat on our mission to save the queen or whatever. For murder sword food.
  Still one of my favorite campaigns. I do think he regretted giving me an excuse to derail his campaign to go murder-hoboing, though.
  
  I'm not going to beat them to death, just beat them until they have detached retinas, are deaf, and are crippled enough to be incapable of revenge.
  I'm not a barbarian, just a human fighter.
  
  It's okay. They've all just had their minds warped by bourgeois propaganda.
- Your #1 challenge and task as a DM is to stay ahead of the players.
  Fighting everyone you meet? Guess what you're in a survival adventure now hiding in the hills because the whole king's guard is scouring the hills trying to TPK the party after they killed the shopkeep.
  OH I BET YOU'D LIKE TO BE ABLE TO GO TO THE SHOP, WOULD YOU NOT
  It's okay, there is an orcish caravan coming through. They want to fight you, but maybe with some skillful rolls you can talk them into doing a little trading through the 1-2 of them that speak common, at least get some food and heal potions and crossbow bolts. You can get kitted out at least well enough to make it a few weeks' journey in any direction and hope the heat dies down before you all get killed.
  OH YOU FOUND A DUNGEON ON THE WAY, LET'S DO SOME FUCKIN FIGHTING
  WHAT DO YOU MEAN YOU DON'T WANT TO GO IN THE DUNGEON, I THOUGHT YOU LOOOOOVED FIGHTING YOU FUCKIN COMPULSIVE FIGHTING PEOPLE
  Guarantee when they get to the next continent for their fresh start (if they make it without the TPK) they will be more amenable to being nice to the NPCs. Or, maybe not, maybe they will have enjoyed the whole process and we get to do the whole thing again, which is also fine and also pretty funny tbh.
  
  To be clear, I don't kill anyone. I only beat them until they will never recover enough to seek vengeance.
  We can make it funnier. I have a resurrection artifact that is cursed, every time I am killed and get resurrected I age 5 years, but beating a human in unarmed combat makes me one year younger. There is no dying of old age, I keep coming back older. So either I am a feisty frail old man or I end up a kid that people have to kill because I don't stop attacking until my 20s.
  
  Then you have the opposite end of the spectrum where my Wizard and the party Rogue were accidentally competing with each other as to who spoke more languages. My wizard won that battle by hitting 21st level first and taking Polyglot as her first epic feat.
  We managed to negotiate a peace treaty with the local orcs, and even got them to send an army to help us deal with a much bigger problem.

Bruh I picked human fighter, not human talker

Still better than a party of 5 wizards all trying to be clever and quirky about any and all details.
- so not a fireball firing squadron?
  
  That comes later when they are all in a confined space.
- "I use a cantrip to cover them in grease then catch it on fire so they keep falling while burning to death."
  Eye roll
  
  Grease isn't a cantrip, and it stops being slippery when ignited. Nice try though, Mr. Clever Wizard Guy.