The latest crop of gravitational waves brought a puzzle. The LIGO, Virgo, and KAGRA detectors caught dozens of signals from merging black holes, and the mass plot shows a glaring gap: objects heavier than 45 Suns are almost absent, and the few that exist spin suspiciously fast. Some say giant stars explode too 'cleanly,' leaving nothing behind. But there's another idea: black holes lose weight before they're even born, in a tight dance with a companion.

Two stars orbit close together, like figure skaters holding hands. One puffs up, and its outer layers spill onto the companion. If the transfer is generous, more than half the material goes, the first star is left as a bare core. It then collapses into a black hole, but a lightweight one: not 50 Suns, but maybe 30 at best. The second act is a reverse transfer, but stingy, with almost no losses. The second star gains mass, but its ceiling is set by another law: that same 'suicide explosion' that leaves nothing heavier than 45 Suns.

In the end, a pair rarely produces two heavy black holes. The smaller one rarely exceeds 45 Suns: it was 'eaten' in childhood. The larger one can grow to the limit, but not beyond. This creates a false 'mass gap' that looks just like the signature of special explosions. Future signals will help distinguish the scenarios: if black holes with fast, aligned rotation or, conversely, lazy rotation are found in the gap, then it's not about explosions but about how the stars shared their matter.