Prince Chid is the heir to duchy of Freid and is supposedly the Duke of Freid and Princess Marlene's son, but his real father is Allen Schezar.

When Princess Marlene had married Duke Freid, she never openly revealed the truth behind her pregnancy, but she wrote about it in a hidden diary that was later found by Millerna. Chid displays a strong connection and trust for Allen, though unaware of their true connection as father and son. After Duke of Freid died, Chid eventually became the Duke.

(Source: Wikipedia)

In the 1994 manga, Chid appears playing the same role of Duke of Freid after his father's death. In the manga there is no relation between him and Allen or the Asturia royal bloodline.