Street Fighter

You were trained on the streets. While the rich and privileged were trained in things like how to use a sword, you were forced to rely on your whit speed, hand to hand fighting, grappling, and underhanded fighting tactics. You spend many years fighting in places like, bars allies, and even fighting pits trying to earn a living. While some warriors are elegant you are a brute clad in whatever you could scrounge together. Pit fighters and bar brawlers typically belong to this archetype. 
A ruffian excels in using their environment to their advantage in single combat and can fight with just about anything while taking a hit or two. 

Ruffian

When you choose this archetype at 3rd level, you learn how to fight in a variety of unconventional ways. You gain proficiency in medium armor, unarmed strikes, and improvised weapons. Your unarmed strikes and improvised weapons deal 1d4 damage and you can use Strength or Dexterity as an attack and damage modifier for improvised weapons or unarmed strikes.

underhanded tactics

Starting at 3rd level, your confidence propels you into battle. You can use a bonus action to try to grapple or shove a creature within 5 feet of you to the ground.

You also gain additional ways to use your Sneak Attack; You may make a sneak attack with any weapon that does not have the heavy property, including your unarmed strikes. The other requirements of sneak attack still apply to you.

Bob and Weave

At 9th level, your fighting skills have given you the ability to counter melee opponents and dodge their blows. When a creature within 5 feet of you makes a melee attack against you, you can use your reaction to gain the benefits of the dodge action. Additionally, when you use this feature, you can attempt to grapple or shove the creature as part of the same reaction if the creature misses on their attack against you.

Ground Game

Starting at 13th level, you are a master of street fighting. If you move at least 10 feet in a straight line towards a target and take the attack action, you can knock the target prone or grapple the target as part of the same attack if it hits. Additionally, if a target attempts to grapple you and fails, or you use an action to successfully escape a grapple, you can use your reaction to attempt a grapple against the same creature.

ground and pound

Beginning at 17th level, your mastery of hand to hand combat has let you excel at attacking at the right moment. You gain expertise in Strength Athletics and Dexterity Acrobatics if you do not already have it, or choose to gain expertise in two other skills if you do already have expertise in these skills. Additionally, you gain advantage on Strength Athletics Checks and Dexterity Acrobatics checks to attempt to grapple a creature or free yourself from a grapple.