If you stepped through a portal into a magical realm and had to choose whether to stay there permanently or live permanently in this world with no chance of revisiting the other one, what would you do?
Doubtless the choice would depend on the nature of that other realm and your happiness or unhappiness in this one, plus the presence or absence of vital relationships in your current life. Seanan McGuire's "Wayward Children" series, so far comprising EVERY HEART A DOORWAY, DOWN AMONG THE STICKS AND BONES, BENEATH THE SUGAR SKY, and IN AN ABSENT DREAM, centers on a boarding school for children and teenagers (mostly the latter) who have returned to mundane reality after living in other worlds. EVERY HEART A DOORWAY takes place at the school, founded and run by a woman who visited such a realm in her own childhood, and the subsequent novels tell the stories of various individual students. Their parents think the facility is an institution for "troubled" youth, but in fact it's a refuge for those who no longer feel at home in this world and yearn to go back to their true "homes." Only in this place can they speak the truth of their experiences without being considered mentally ill. Whether wardrobe, looking glass, rabbit hole, cyclone, enchanted picture, or whatever, most portals open only once. Some travelers find their doors again, but that happens rarely. For those who make the transit multiple times, such as the protagonist of IN AN ABSENT DREAM, there's always a final trip. The heroine of that novel faces a deadline; by the time she turns eighteen, she must make an irrevocable choice.
Of course, this premise inevitably brings Narnia to mind. The characters in EVERY HEART A DOORWAY discuss that series at one point, remarking on how the children get to visit Narnia several times, through a different portal on each occasion. One of the characters says C. S. Lewis didn't know what he was talking about; he might have heard rumors about children traveling to other worlds and just decided to develop the concept for his own narrative purposes. "That's what authors do, they make [stuff] up." In THE LAST BATTLE, all the "Friends of Narnia" get to stay there at last—except for Susan, who has managed to convince herself that their adventures were only games they'd played in childhood. (In one of his letters, Lewis says Susan may have eventually gotten back to Narnia in her own way.) Visitors to Narnia, however, don't control when they go there and return to Earth; they cross between universes by the will of Aslan. Even in THE SILVER CHAIR, when Eustace and Jill ask to be taken to Narnia, Aslan says they wouldn't have called on him unless he'd first been calling them.
In THE LIGHT BETWEEN WORLDS, by Laura E. Weymouth, three children are transported from their backyard bomb shelter in World War II to an enchanted country ruled by a lordly stag. As in Lewis's stories (and unlike in most of the alternate worlds mentioned in McGuire's series), the characters return home at the moment they left, so their parents never know they were gone. Several years later, in the postwar period, one girl remains obsessed with getting back to the magical realm, while her sister simply wants to move on with her ordinary life.
Claire, the heroine of Diana Gabaldon's Outlander series, faces a similar dilemma, in her case dealing with time travel rather than cross-dimensional travel. When she finds herself pregnant just before the battle of Culloden, she chooses to return to the twentieth century and her first husband for the unborn baby's sake. Twenty years later, when her circumstances have changed, she ultimately decides to return permanently to the eighteenth century and the love of her life in that era. Her first trip through the stone circle happens by accident, while the other two result from her own choices.
If I had the chance to visit Narnia during one of its peaceful periods and meet Aslan, I would, but only for a visit, not to stay. On the other hand, if I'd been offered such an opportunity between the ages of about eight and sixteen, I would have joyfully leaped at it and remained in the magical realm permanently. From my own experience and what I've read, it's not uncommon for a young fan of fantasy and/or SF to have a strong feeling that "there must be a place where I belong, but it's not here." Indeed, that's probably an important factor in making us fans in the first place.
Margaret L. CarterCarter's Crypt