Much like faerie food – to which it may be related – Heroine is a substance found in all plants growing on a particular planet. It is sometimes referred to as a parasite, suggesting that it may be some sort of fungus infecting the plant life.
The effects on users are broadly similar: it will cause them to hallucinate the presence of someone emotionally important to them, who will implore them to stay on the planet using whatever arguments seem most likely to be effective – up to and including encouraging those affected by it to murder others. Fortunately, the risks of Heroine are reasonably well-known, and the effects wear off quickly once it is purged from the body of the consumer.