Originally an intentional journey for some exploratory / scientific purpose a young man becomes stranded on a time-shifted planet/forest of perpetual winter (or perhaps he was sent back in time to the last ice age but stayed too long and cannot come back). Scientists and solders visit him periodically and praise his efforts, always framing it as a noble endeavor but then returning to their time. He accepts his situation and makes the most of his new life. Sometimes he will recognize a visitor from a visit years before since they look exactly the same and only he has changed and grown.
One day a small floating white sphere (~1-2in) appears near him and silently follows him wherever he goes. He spends a lot of time around a frozen pond and on a path surrounded by tall grasses. Suddenly after a time the sphere speaks to him with the voice of a Japanese woman. As she speaks the sphere glows; expanding and shrinking slightly with the lilt of her voice. Conversation is stilted at first but over time a bond begins to develop and as days turn into weeks turn into year they develop a deeply meaningful relationship.
Years pass and one day the sphere, always at the now man's side, suddenly goes dark and falls silent to the ground. Confused and concerned about the disappearance of his companion the man travels back to the first grove, the place where he first emerged into this everlasting winter. Sure enough several scientists from the future appear, rushed and harried. They explain that much has changed in the years since the man left his time.
They reveal to him a devastating secret the sphere was not some alien or person speaking to him through time but an AI that the future had been developing. They found that every time it spoke with him through time it would make leaps and bounds in its complexity and understanding of the world. What had started as a simple experiment had gone far further than anyone could have imagined and with his companionship started to become something beyond a simple AI. However the future is not longer the scientific utopia it once was and a religious order is making a power play for the AI. Led by a conniving priestess the AI's connection to the man was severed and the order's motives and plans are unclear.
Distraught and furious about the uncertain future of his friend he, through force of will, is able to find a way back to an unfamiliar techno-future. Unintentionally proving that, on some level, he was always able to return but never wanted to, preferring the simpler life of cold isolation. Thrust from a world of snow and trees into one of glass, steel and flying vehicles the man journeys to the high-rise temple to confront the priestess. He looks very out of place with simple clothes a long beard and a twisted staff, on top of which the silent sphere has a place of honor.
As he moves up this glass high-rise using a twisting staircase as wide as the building he begins to recognize this as the former building where he was first convinced to take the journey to the time-shifted planet. Now the tower is no longer the hotbed of science and sophistication it once was. Men and women cluster on the sides of the stairs, clad in revealing ceremonial garb and casually gossiping. As he gets closer to the top of the tower he begins to notice just how much attention he is drawing with his strange appearance. People reach out to talk with him, touch him, trying to catch his attention or a piece of him. He has spent his time away working on himself and his aura of focus and confident otherworldliness intoxicates the people who's life consists of idle pleasures and has never extended beyond this tower.
Finally he approaches the top of the stair where the priestess is flanked by her meek fiancé . Wrapped in arrogance and a cocky smile (think Zafirah from Book/Past Due) she hungrily welcomes him home as if getting him to her was the intent all along.