Complex sentence: He accidentally discovers the lab and the Rats after he and his mom move in with Davenport and finds them, as well as Davenport's inventions, to be incredibly cool and quickly forms a sibling bond with the Rats.
Split into simpler sentences: He accidentally discovers the lab and the Rats after he and his mom move in with Davenport. He finds them, as well as Davenport's inventions, to be incredibly cool, so he quickly forms a sibling bond with the Rats.