Hold Master

A fighter subclass dedicated latching onto enemies and either tossing them around like nothing or gripping them tightly and choking them into submission.

Improved Unarmed Strikes

3rd Level: Improved Unarmed Strikes: The Grappler's unarmed strikes deal an extra 1d4 damage, this increases to 1d6 at level 5, 1d8 at level 11, 1d10 at level 15, and finally 1d12 at level 18. Additionally, the target must make a strength saving throw (DC 8 + proficiency bonus + strength modifier) or you get to immediately make a grapple check.

Special Fighting styles

3rd Level: Special Fighting styles: The Grappler Monk can chose from two fighting styles, "Submission Fighting" and "Throw Fighting". "Submission Fighting" grants use of submission holds, which focus on preventing an enemy from escaping you while you slowly whittle down their health, and +2 to grapple checks, while "Throw Fighting" grants advantage on grapple checks and provides access to special throws so you can fling your enemies across the battlefield.

Submission Fighting

This fighting style focuses on using submission holds and techniques to wear down opponents and make them submit. You gain the ability to add your proficiency bonus to grappling checks.

Throw Fighting

You've trained your body to throw your enemies around the battlefield like dolls. You gain advantage on all grapple checks.

Grappling Mastery

3rd Level: Grappling Mastery: The Grappler can grapple up to 2 creatures at once.

Opportunistic

6th level: Opportunistic: Whenever an enemy within 5ft of you make an attack you can use your reaction to make a grapple check against them.

Improved Movement

11th Level: Improved Movement: The Grappler's movement is not hampered by difficult terrain when grappling an opponent and can move through threatened squares without provoking opportunity attacks if grappling an enemy.

Paralysis Hold

17th level: Paralysis Hold: While grappling an enemy you can use an ancient technique to lock up their muscles and paralyse them for a number of turns. Does not work on enemies without muscles or a corporeal form.

Grants the Paralysis Hold action. Has a number of charges equal to strength modifier. Charges replenish on a long rest. Target must make a Constitution saving throw (DC 8 + proficiency bonus + strength modifier) or become paralysed for 1d4 turns.