The Imprisoned

Your Patron is a being of immense power, more so that usual warlocks. it was once a ruler of some sort and was taken down, imprisoned and chained down, suppressing its power. But not enough to not be able to grant mortals power. This patron has given you power because you have agreed to seek it out and help free it. Warlocks who have made deals with The Imprisoned One often adopt this signet and where broken chain cuffs or incorporate chains into their aesthetic in some way.

Bracers of Tribute

Starting at Level 1 your Bracers of Tribute are your Arcane focus and give you an extra +1 to your AC. You can also impose disadvantage on a grappled creature for its next saving throw to get out of being grappled. You can do this a number of times equal to your charisma modifier (minimum of 1). your regain expended uses of this feature after a short rest. You can add your proficiency bonus to contested strength checks for grappling.

Ethereal Chains

At 6th level, you may summon chains from each of your Bracers of Tribute as a bonus action. These chains have the light and finesse features for you. When you summon them, you may choose Striking Chains or Binding Chains. These chains disappear if you use a bonus action to dismiss them or you fall unconscious. No other creature is able to use them.

Bound Affliction

Starting at level 10, you can use your action to hurt a grappled creature. Use an action to make a contested Strength check against a creature you are grappling with both chains in your Binding Chains feature. If the creature loses the check, you deal 2d8 force damage to it. if it wins the saving throw, deal half damage to it. It has advantage on its next saving throw to get out of being grappled. The damage die increases by 1d8 at level 14 and again at level 18.

Enslaving Cuffs

Starting at 14th level, you can enslave one creature. When you use your Binding Chains, as an action you can use this feature. The creature must make a Wisdom Saving throw against your spell DC. On a successful save, the creature is no longer grappled but frightened by you. On a failed save, cuffs similar to your Bracers of Tribute appear on the creatures wrists. In it charmed by you until the cuffs are removed. These cuffs are magical and can be removed with a Remove Curse spell or other spells similar to it. The cuffs are also destroyed if you use this feature on another creature or the creature dies. The creature will fight along side you if it usually would do so with other creatures that are friendly to it, and will generally listen to you. Its personality doesn't change. When the cuffs are removed, the creature is extremely hostile towards you, if it is alive.