No one got them. One was seen as cold, calculating, controlled. The other was as cheerful and reckless as was possible in a pilot.
It took a long time, even for their friends, to see beyond the masks they both wore, to understand how they had found each other to be the right fit to their inner selves.
Neither Heero nor Duo really cared to explain it anyway, just knowing that for all their differences, they were well-matched where it mattered. Comfort needed, given, shared kept them going even when the odds stacked against them. No one else mattered then.