A subplot may not be as important as the main plot, but for me, it still serves a big impact to whatever you are writing. While they may not affect the main plot at all, they can bring a lot of life in whatever way to your story and that is exactly why I love subplots. They flesh out aspects in your story; they build your world; they put pieces together.
In RPs, subplots are just as common. It is mostly noticeable between two characters from two RPers who planned a relationship out. Now, of course we will want them around us, because they are also what makes roleplaying very interesting. But if you are planning to, here are tips to keep in mind if you need help!
Think of what kind of subplot you are doing.
There are different types of subplots, most common being romantic ones. To create an interesting subplot, you have to consider what type of subplot you are making first so you’ll be able to know how to carry it out. For example, if you want a romance subplot, then you’ll have to think about how it will begin, how it will be developed, who are going to be involved in it.
Make it with a purpose.
Why are you writing this subplot? What purpose will it serve to your character? Will it expose something? Will it show a side we need to see?
Connect it to the character’s main idea.
Just like in books, you should connect your subplot your the main idea. It should be able to explain a certain aspect or behavior, expose a certain aspect or behavior, support something, etc. that can be traced back to the character’s background.
Make it so that your subplot develops more conflict or increases tension.
We all love tension and conflicts, and they are what makes a character more interesting. Let your character subplots have that and you’ll have a number of eyes curious on what’s next 
@RPers, I hope this will help you somehow! Also, feel free to leave a tip of yours too
