TL;DR for all this nonsense: It might be possible for Harry to learn to reach/leave the Sepiaverse on his own, if he follows Charlotte through once. If we close an access point, we fix the interference for good. Here's some science! The "Sepiaverse" is a reality much like ours. Visitors have reported an unexplained optical effect on visiting. This may be an element of the atmosphere or some basic property of that space. There are connection points between the Sepiaverse and normal space. These points are anchored with respect to our Earth's rotation and motion. We observed interference with electrical systems and electromagnetic radiation around one such point. Traversing a connection point expands the boundaries of the interference. Charlotte was apparently solid on the Sepiaverse side. Two points in space cam be connected via wormholes - tunnels through spacetime. Wormholes are theoretically stable with a negative energy density, usually requiring exotic matter or the like to maintain. Hypotheses: Connections to the Sepiaverse are wormholes. Electric systems and EM are affected because some amount of energy is siphoned into the wormhole. This would strongly impact conventional electronic devices and weakly impact the electrochemical nervous system of living things. The interference can't be too strong, or living things would die during the transition. Testing: strong EM waves emitted on one side of a wormhole could be weakly detectable on the other side. Verify this by checking for emissions from our radio on both sides of the divide. Whatever is maintaining these connection points may have a regulator mechanism - something that ensures the wormholes stay open. Or, positive energy traversing a wormhole may naturally give rise to negative energy to counterbalance the mass. Testing: correlate energy density with increase in the area of the interference Speedsters may bypass relativistic limits via a similar mechanism - if they are able to effectively move partially through a space where momentum is negative, they can achieve otherwise anomalous speeds. If so, this would explain Harry's ability to enter the Sepiaverse aided by Alycia Chin - she oriented his body in the direction of this space, causing him to reach the Sepiaverse "naturally", or at least be "pushed" through the membrane. In this case, once the effect wore off, Harry would naturally be pulled back. It is possible that Charlotte is really a projection from the Sepiaverse, working in reverse - her immaterial body here is an echo or "glove". If so, it might be possible for Charlotte to "orient" Harry and teach him how to reach the Sepiaverse unaided. In other words, rather than Alycia's power jolt supplying the outside force, Charlotte herself might do so.