Questions raised:
1. Do dimensional connections in addition to Angelus Errare exist in varying levels of strength?
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1. Dimensional connections
Empiric
In addition to Angelus Errare, a few other connections between the dimensions exist around El Nido, varying in strength. This means that actions in a certain area in one dimension may have repercussions in the same area in the other, and so on. While Home and Another run parallel to each other, there are some connections. These can be readily observed by the well-traveled; here are a few cases.
1. During the fire at Hermit's Hideaway in Another World, a patch of ground was charred and smoldered for days after. In Home World, the same patch of grass seemed to be fine; nothing notable happened there. Once the charred area was cooled by the Ice Gun or Breath in Another World, Turnip sprang to life in the same area in Home World, apparently thanks to the cooling of the grass in the other world, which enabled living or growth conditions and allowed Turnip to flourish.
2. Concerning Turnip again, he is stated to be the dream of an Acacia Dragoon -- in Another World. The dream apparently transcends the dimensions; Turnip notes that he dreams he is the Acacia Dragoon when he sleeps.
3. The Black Dragon of Marbule shares a similar dream. From Another World, his nightmare casts a gloom over Home World's Marbule, filling it with Lagoonates and Mantarreys.
4. In Shadow Forest, a rock exists in the fast stream coming from Viper Manor's water system. If you roll it over the water jet in Another World, it is rolled in Home World as well, and a man is trapped behind it. The same happens conversely; if the rock isn't rolled, the mushroom collector is threatened by enemies instead.
More interesting is whether dimensional connections exist between people, and whether actions in one world are balanced out by actions in the other concerning the same person. Some lead similar or the same lives, while everyone around them lead drastically different lives because of the split. Perhaps they, themselves, have a very thin dimensional veil, causing little difference to come about. And, then, the ones whose lives have the most difference would logically have thick veils about them. The same would go for areas in which the same monsters roam in both worlds; perhaps these areas are so unaffected that their environment has not changed in the least!
Perhaps when dimensions are split, some links or entities have stronger inward compositions or some other physical phenomenon that result in them running a bit closer to each other. Think of two planes set atop each other with space between; some points dip, nearly touching each other, while the only tunnels between the two are Angelus Errare and the FATE Island distortions in the Sea of Eden. In any case, connections between persons is tenuous except in the case of Orlha and Tia, who seem to be equivalents of one another though somehow different in identity.