So, I decided to go back and finish the Magi series (as a Manga) and realized something, there are a few characters that have something similar to a Genie patron Warlock relation, and there's something that looks like it might be a bit of a display for a type of pact we haven't seen in official play yet. I highly recommend checking out the Magi series, as a Manga (finished its run with 369 chapter) or anime (which was technically broken up into 2 different anime series but never finished a run to wrap up with the manga), it can potentially give some ideas. Okay, now that the pitch for a series I like is over, on to what we're all here for.

In the Magi series genies go to those that conquer their dungeons, they do this by inhabiting a metal object the "dungeon conqueror" had on their person in some way, it could be a weapon like a sword or a dagger, an accessory like a fan or hairpin, a piece of armor, or just a random piece of metal the person had on them at the time, it didn't matter. Now, there's a lot of story potential there and the genie vessel rules could potentially be modified to fit this. But that's not where I'm going, I think it would be interesting to see, but where I'm going is different. When a genie inhabits a metal object, in Magi, it becomes a genie vessel but it's also known in series as a "Metal Vessel" and that's where things start to get interesting, metal vessels have the power to imbue magical abilities into other metal objects, what Magi calls "Household vessels" but they don't actually need to be something you would associate with a household. Household Vessels grant their wielders special magical benefits, or just act as magic items with a few extra properties, but they only work if the Metal Vessal user isn't apart from their genie vessel, if the Metal Vessel user is separated from their genie vessel then the Household Vessel of that Metal Vessel lose the special properties they were granted until the Metal vessel user is reunited with genie vessel.

All of that screams Warlock Pact to me. We could call it something like Pact of the Vessel. This pact could do something like allowing a portion of your patron's power to reside in one metal object on your person, potentially more as you level up, and could allow you imbue the metal weapons and items of yourself and your companions with properties associated with your patron. This way you could have a Warlock that can potentially alternate between a more aggressive character and support as needed. Also, these imbuing would be longlasting and would not require concentration to maintain. However, there would be one major downside to this pact, if the Warlock with this pact bites the dust then all benefits their equipment and equipment they imbued are immediately lost, which would mean they would have to spend an hour or more conversing with their patron to reimbue the power in the vessels they had on their person that were imbued by the power of their patron (and they would have to go through this for each individual vessel they had on their person at the time).

Just like with most Warlock stuff, there's a lot of story potential here. The idea of a portion of your patron's power being within your immediate reach is always a fun concept to think about, and having it reside in any metal object means you can slip it by guards who are only on the lookout for weapons and the like.

Well, that's everything I had to say here, what are your thoughts? Are there any other types of pacts you've thought up or about?

Well it takes away from genie, and steals their flavour. Like the idea though. 

I gave it a "sounds interesting." It has potential. But instead of kinda sorta stealing from Genie, and maybe a bit from hexblade, I'd make it - and it's expanding metal-based powers - a function of Invocations.

At 3rd level, you get your pact boon, and that shapes your Invocations, too. Soo, we'll take the pact of the chain, and now you could, for example, armor your familiar or similar. At later stages, maybe you and your familiar could make melee attacks. I don't know, as I'm thinking while I type, but there's potential. 

Were I to DM such, I'd rule it as a reskin of Genie and allow it. I'd definitely want a good session zero before the character entered a party at any level, as homebrew things like this require at least some explanation. 

I know the wording made it sound like I was cribbing from the Genie Warlock, but I was actually writing a modified layout of the early abilities we see those with djinn in Magi get, things just sound like a genie patron because genies are what are used in the series. I suppose Magi could be a good example of what Genie patron Warlocks could be at early and higher levels. One of the more advanced abilities in Magi for those with djinn is an ability that sounds like it could very well be a D&D ability in the future, the "Djinn Equip" and that is one crazy ability. Djinn Equip, which I'm surprised nobody has suggested over the course playtest for the Genie patron Warlock at this point, is an ability that allows the user of a Metal Vessel to more or less merge, but not fuse, with the djinn in the Metal Vessel for a short time, time limits vary by individual personality traits and how well they actually synergize with the djinn they are equipping. Those with a strong force personality, High Charisma with a history of excellent Charisma-based rolls in D&D terms, tend to have a natural ability to hold djinn equips longer and perform them more easily than those less of a force of personality.