Question: What if one black hole sucks another and another?

Bella Boulderstone answered on 18 Jun 2019:

Black holes are tricky! So the stuff that causes the ‘sucking’ is gravity, which is just the same as what causes the Earth to go round the Sun and the moon to go round the Earth and what keeps you on the surface of our planet! It’s more like things fall into black holes, rather than being sucked into them.

How big a black hole is depends on how much stuff there is inside it (all squished into one teeny tiny point), having a bunch of black holes fall into another one would make the first black hole really quite big.

In fact, this is how we think supermassive black holes are born, smaller black holes collide into each other, releasing massive amounts of energy (gravitational waves come from these types of collisions)!