You specialize in kidnapping other creatures. Inflicting the restrained condition, you can gain advantage without a problem. Dragging them away from the fight, you silently attack them while striking fear in their allies when they notice one of their friends is gone. 

Bonus Proficiencies

When you choose this archetype at 3rd level, you gain expertise in Athletics. You also gain proficiency in Intimidation.

Master Captor

Starting at 3rd level,  you can use your bonus action to attempt to grapple creatures. You have advantage on your grapple check if you are flanking the creature you are trying to grapple. Also, when you grapple a creature, they suffer from the restrained condition. Additionally, you don't suffer movement penalties from grappling a creature. After you have grappled a creature, you can attempt to drag them away from the fight. If you want to remain unnoticed, you will need to roll a stealth check. If a creature you are grappling has no allies within 15ft, you gain the following effects.

They have disadvantage on breaking out of the grapple.

You can still use your sneak attack for the next minute even if they get out of your grapple, as long as you don't have disadvantage. 

You can attack twice against that creature, though you can only use your sneak attack on the first attack. 

Human Sheild

Starting at 9th level, while you have a creature grappled, you gain a +2 bonus to your AC.

Diverting Threat

Starting at 13th level, you can use your reaction to alert creatures to their ally's disappearance.This feature only works when you have grappled a creature and they are heavily obscured. This does not tell enemies where you are, but will only alert them that the creature you abducted is gone. The first attack on each of your ally's next turns have advantage.  Also, you gain advantage on Intimidation checks. Once you use this ability, it can't be used again until you finish a long rest.

Frightening Grasp

When you grapple a creature, you can choose to inflict them with fear. Starting at 17th level, you can force a creature you are currently grappling to make a Wisdom saving throw with a DC of 8 + your proficiency bonus + your strength modifier. This takes no action. On a fail, they are frightened for one minute. They can repeat the saving throw when an ally enters within 5 feet of the creature. Once you use this feature, you cannot use it again until you roll initiative.