Prince and Princess Ludwig von Hesse-Darmstadt. Prince Ludwig was the last surviving member of the Hesse-Darmstadt ruling family. After his death, the Darmstadt claims & property passed to the Kassel branch of the Hessian ruling family.
Prince Heinrich (right) and Prince Moritz of Hesse-Kassel, the 2 eldest sons of Prince Phillip and Princess Mafalda. I think Prince Moritz favors his mother in this photo while Heinrich favors his father even though he looks more Latin than Teutonic.