[@Vixen58]
Sure, if you are still interested, I can provide some assistance:
Things to look into:
[list]
[*][b][u]Character Sheet:[/u][/b]
There are a few online character sheets that you can use, but [url=https://dicecloud.com/]DiceCloud[/url] is one that I like as it helps with calculating some numbers. Also to help understand how to use the DiceCloud, I would recommend this [url=https://homebrewery.naturalcrit.com/share/rkZujQwpQW]tutorial[/url] that you can read through to help.
[*][u][b]Race:[/b][/u]
For human, you can choose one of these 2:
Standard - which increase all of there ability score up by 1.
Variant - which increase two ability scores of your choice, choose one skill to be proficient in, and choose one [url=https://www.jsigvard.com/dnd/Feats.html]feat[/url] of your choice.
[*][u][b]Class:[/b][/u]
As you already stated Aron being a fighter, you can try looking on this [url=http://dnd5e.wikidot.com/fighter]page[/url] at a what you can have as a fighter at level 3. One of those things being a subclass, so you can try to choose one that you feel fits for Aron.
[*][b][u]Background:[/u][/b]
Background [url=https://5ebackgrounds.com/]list[/url]
From what you mentioned in Aron's backstory, I feel his background could be a "Guild Artisan" as it includes smithing.
[/list]
This is just a general information to get an idea of what you can choose from as mentioned from your previous. If you have any questions, just let me know.

[@Guardian Angel Haruki]
The djinn's name would be Ralim, the Ever Curious Curator. I also had some fun writing about Ralim and thought I would share. Please let me know what you think and if you're okay with it.

From the title and living under his care, Najila would that has quite the varied collection of things that he basically made a museum/house to store and categorize them all. He would mention that it began about 250 years ago when mortal was kind enough to use their wish to release him from his lamp. Ever since then decided explore and see various places than the simple interior of his prison of a lamp. After enjoying exploring the world and planes enough, he decided to take souvenirs to remember those places, eventually forming his museum, the Cosmological Sanctum. 

The Cosmological Sanctum, home to wonders and mundane things across the plane. It is likely here that Najila learned many things of the world as there are many, many, many displays of things to show. Although there are other planes, not all were shown, as those rooms can be quite dangerous for a simple mortal to enter in as there are a few rooms that simulate the planes the house. But he would usually say that the room material plane is a bit easier to relax in after working in the other one. For the material plane rooms, Najila would typically be allowed to usually wonder freely, one of these being Najila's own room.

When it comes to business, would you know that Ralim hates being requested to do the typical genie wish. But depending on on the person and the wish, he may go along with listening and doing the request, then he will try to make a spin on the wish to basically prank the person, either temporarily or permanent.