Running Into Time by Cedar Sanderson

A short tale. It involves Pol, who's researching time travel, his twin sister Oly, and Garry a classmate of Oly's. Also a government agent who was sidelined by his injuries when Pol's research had the government activate him again.

People come after them. Pol goes to protect Oly. As a consequence, we follow the adventure of Pol, along with the test mouse Gus, and the adventure of Oly and Garry as the first humans affected his device and so operating blind. It involves adventures and difficulties and discoveries about what Pol discovered.