Quiet black holes that orbit a companion star are challenging our understanding of how these cosmic objects form. Unlike active black holes, which emit bright X-rays and powerful jets that are easily detected, quiet black holes do not consume material from their surroundings. This makes them much harder to spot. Instead, astronomers infer their presence by observing the gravitational effects they have on nearby stars. Recently, the Gaia spacecraft has identified three such quiet black holes, each orbiting a smaller companion star. These discoveries are significant because they suggest that these black holes once had massive stellar companions that have since collapsed into black holes. Gaia's main goal is to map the positions and movements of over a billion stars in the Milky Way. To do this, it measures tiny wobbles in a star’s motion, which can be caused by the gravitational pull of a nearby object. Usually, this object is a planet, but in three cases, the gravitational tug was so strong that the companion must have a mass similar to a star. However, Gaia did not detect any visible star in these systems, leading scientists to conclude that the companions are black holes. Each of these black holes is paired with a smaller, visible star, which implies that the systems were once asymmetrical, with one star much larger than the other. In one of the systems, Gaia BH3, the binary pair is far apart, which aligns with expectations for how such systems form. However, in the other two systems, BH1 and BH2, the stars are much closer together. This raises a key question: how did the smaller stars survive the expansion of their massive companions during the latter stages of their life cycles? When a massive star nears the end of its life, it expands significantly, potentially engulfing a close-orbiting companion. This would cause the two stars to merge, rather than forming a black hole and a companion star. One possible explanation involves a process called Roche-lobe overflow. This occurs when the outer layers of an expanding star extend beyond a critical region of space called the Roche lobe, where its gravity is strongest. If the material expanding beyond this boundary is diffuse enough, the smaller companion star might be able to capture it without the two stars spiraling into each other. This process could allow the smaller star to remain in a stable orbit long enough for the larger star to collapse into a black hole. While the Roche-lobe overflow model is one possible explanation, the current data is limited, and more observations are needed to confirm this theory. These findings highlight the complexity of black hole formation and underscore the need for further research. The study has been published in The Astrophysical Journal.