The "Last Key", was the name given to the youngest member of the group, who also happened to be the oldest.
The old dwarf's name was Olfa Kanthil, a man who once belonged to a prestigious family of protectors who had protected the lands of dwarves for a century at this point.
A family started by his father, who in a bid to create a clan on the same level as the Ancient ones, did the unthinkable and stooped so low as to marry more than one wife in his life.
A fact that is highly looked down upon in the dwarven society. As for them, they usually mate for life. Either by love or by arranged marriage, once married, a dwarf never falls in love once again or marries another wife.
But Olfa's father didn't care for such a tradition. The shame can be washed through achievements, it was only temporary. But a greater family that may go down in history was more important to him.