Master Grappler

You've become a master in close-quarters grappling. You gain the following benefits:

• You can initiate a grapple by making a Dexterity (Acrobatics) check instead of a Strength (Athletics) check.
• You can use an opportunity attack to make a grapple check.
• When throwing a creature grappled by you to knock it prone (shove action), the creature suffers bludgeoning damage equal to 1 + your Strength modifier when falling prone.
• You can spend a few turns to perform a blood choke against a Large or smaller creature you are grappling. You must have both arms free to execute this maneuver. In the case of a Large creature, you climb onto the back of the creature as part of the maneuver. To succeed the blood choke, you must succeed additional grappling checks equal to the target's Constitution modifier (minimum 1). Each one of these grappling checks requires an action. If you fail a check, the creature remains grappled, but you have to start the blood choke over again. If you succeed the required number of grappling checks, you subject the creature to the unconscious condition. The condition lasts for 1d10 minutes or until someone uses an action to shake or slap the creature awake. It also ends if the creature takes damage. This maneuver doesn't affect creatures that don't need to breathe such as undead, plants or constructs. The DM may also rule that heavily armored creatures are protected and can't be strangled.

Variants: 

The DM can make these benefits part of the default Grappler feat.

The DM can increase shove damage to 1d4 + Strength modifier

The DM can reduce the blood choke duration to 1 minute to mimic the effects of the sleep spell.