I haven't been diagnosed for ADHD, but this is relatable! I once tried to explain a video game's lore in my own words to my sister, and I was just all over the place, like:
"...then this guy did a thing and then- oh and I forgot to mention that before this and this happened, another faction did this, which is why this and that happened. Jumping back to where we were before, he then got- oh and btw this is after that one thing happened, but also before this other one. Anyways..."
