Kaplin Longharn (Kap'-lin Long'-harn) is the name of a human guise an unknown black dragon used in the latter 4th Age. It is believed he is a servant of the Elder Dragons who learned through either his own or others abilities in divination that the young Gildanesti girl Aynal Teralshall would be key to the Elder Dragon's victory over a coming enemy not yet in the Midlands.
After locating Aynal begging on a street corner, he scoped her out for several weeks using different appearances. Right before a hurricane hit, he offered to give her shelter. With nowhere else to get protection from the elements, she went with him. He took her to a manor home he had procured and set off to teach her about the Divine Bureaucracy and the Elder Dragons. He also began to subtly teach her how to achieve the mental state (for prayer purposes he claimed) in which she would be able to cast the magic available around the dragon lairs without her realizing it.
Aynal was not the only one ensnared. For unknown reasons, Kaplin quickly fell in love with the Gildanesti girl. The two became lovers, and Kaplin was swiftly addicted to the bipedal intimacy and Aynal's passion. However he did not reveal his true nature to her.
Seasons later Aynal perceived Kaplin was hiding something and confronted him over dinner. He admitted that his taking her in was not a random act of kindness. "Divine magics pointed me to you. I have watched you under many faces for weeks before using the storm to bring you to me. You are important to us, Aynal. How is uncertain, but the one detail of the future is clear. You will be one of the major key players in a coming conflict between the Dragons and a coming enemy. We need you for victory."
She tried to escape from the manor, but Kaplin restrained her. She slashed his neck with a steak knife from the dining table and was almost killed in his smaller weaker form. Instinctively, he began to revert back to his natural form. Breaking out of the building, he hunted for Aynal and found her. However a band of adventurers came to her defense. Still weakened by the brush so close with death, he flew off.
Although Kaplin has never been seen again, it is theorized that the black dragon may watching or hunting for Aynal in another form. It is also possible he is already close to her again. Another theory, one not many are willing to believe in, is that Kaplin was not only a supporter of Divine Bureaucracy but in fact Xyvren, the Black Elder Dragon himself.