Proper way to model a low poly flat 2D object that is created vertex by vertex?

I am trying to create a low-poly cape like this:

With this, I could do a “mirror” modifier and then partially wrap this cape around my character, but I see some vertices that are not connected by edges seem to “connect” to each other somehow when I try to curve the cape around. For clarity, please see the image below:

What I did is just grab the vertex on the right and use proportional editing to move the cape and try to wrap my character. But then as you can see, how come the 3rd highest vertex in this image seem to want to connect to the “tip” of the cape as well as another vertex at the bottom?

My Blender experience is still very limited, so what is going on here? What would be the proper way to tackle this?

It’s because you have an n-gon which is unpredictable during triangulation. Every mesh is triangulated during the rendering stage if it hasn’t been already by the user which every 3D renderer does. If you connect everything manually you will get predictable results that will be easier to work with. I suggest turning your n-gon into quads to fix this issue and if you need it to have smooth results you can use the SubD modifier and set it to 1 step and simple so you don’t have as many vertices to deal with or you can add the extra geometry in manually.

Thank you for the keyword “n-gon into quads”. That made me found this: https://youtu.be/DwpajQ0oQPI

You’re welcome and it’s a good video for what you are doing.