Esper and guide is a symbiotic relationship. The Espers are given super natural powers & abilities far greater than a regular human. The downside to that, is that they go mentally unstable and will die if they use their power too much. Hence that’s what the guides are for. Guides soothe the Espers mentality, helping them to go cookoo. Typically, the esper is to protect their guide.
The guides can go on with their life fine without an esper. But an esper cannot go without a guide. The only way for a guide to perform guidance is through physical touch. The more intimate it is, the better the guidance will be. There’s a thing called bonded pair, and that’s when an esper and guide are bonded for life. That means that the esper can’t take guidance from any other guides besides the guide that they pair, while the guide won’t be able to guide any other espers besides the esper that they pair. Obviously, these are the typical “rules” to guide-verse, but every story can change it to their own.
As for the poison. There are different levels (ranks) between guides and espers. From lowest (weakest) to highest (strongest) is D, C, B, A, S. S ranks for either party is pretty rare. The guides rank can determine who they can guide and who they can’t. And an espers rank can determine how strong their powers are. Guide wise, the higher the rank, the more addicting their guidance is to lower ranks- hence that’s why it’s poisonous to lower rank espers. Guidance addiction is very dangerous for both parties as it damages the mental and physical state of both the esper and guide, that’s why guides can typically only guide: 1 rank down or the same rank. They can’t guide a rank above bc then their guidance wouldn’t do anything to the esper (typically).
Hopefully this helps
they should’ve put like an intro or something to give more depth on this esper and guide thing like how does it work what is the poison and why is there so many unexplained things