Excellent. I love the strangeness and true alienness of these creatures. I am like Manfred; I don't need to know more about these creatures in order to use them in the game - the PCs will interact rarely with them and are certainly unlikely to be able to find out more than what it is told here which is rich in its detail and sense of otherness.
I was thinking about how the PCs could interact with them and thought of the following:
1) Magic - always a copout but definitely a possibility in a high fantasy world. It should be extremely difficult if possible.
2) Perhaps the merfolk bring a trench-folk artefact to the PCs and ask them what it is. It will be utterly alien to anything they or any others have seen before.
3) My favourite. A ship carrying the vital McGuffin, essential to the saving of the world/continent/nation has sunk in a storm, falling into a deep ocean trench. The PCs, via the intermediary of the merfolk, must persuade the trench-folk to return the McGuffin to the surface. The merfolk have no reason to like either surface dwellers or trench-folk and will have to be persuaded to cooperate. They may try to seize the McGuffin for themselves.
In addition, the PCs will have to learn enough about the totally alien society and culture of the trench-folk (via the merfolk - Chinese whispers with much potential for misunderstanding) in order to negotiate with them and try to persuade them to give up the artefact. If the trench-folk learn of its powers would they not wish to keep it? What could surface dwellers possibly offer such a deep-dwelling race in trade? To complicate things still further, perhaps the sinking ship landed on part of a trench-folk city causing great destruction and many deaths; they see it as a hostile attach and will be most unwilling to believe it was an accident. Go to Comment
Really quite interesting. Possibly the safest way to use it would be to throw it as an improvised javelin. Probably wouldn't work against a creature (too hard to aim) but might be effective against a fae enchantment. Go to Comment
Photosynthesiser Mutant is able to photosynthesise, meaning it can generate its own food source as long as there is light. This would also mean that mutant was green, which would be fairly noticeable. It could be entirely green or just have green patches. Go to Comment
The ruling family depends on some magical artifact or place to secure their right to rule. A monarch isn't considered legitimate until he or she has been "accepted" by the artifact or place, whatever that might entail. It is also possible that some one else, not of the ruling family, could be accepted as the legitimate heir... A fact which the monarchs would like to keep secret.