Complex sentence: While maturing, 47 was quiet and showed little social behavior, his only display of affection being toward a runaway laboratory rabbit he adopted much to Ort-Meyer's displeasure.
Split into simpler sentences: While maturing, 47 was quiet and showed little social behavior. In fact, 47's only display of affection was toward a runaway laboratory rabbit, which he adopted much to Ort-Meyer's displeasure.