David

David is a member of the Red Shield. He works as an agent assigned to direct collaboration with Saya.

Joining Red Shield
David was the sole survivor of a chiropteran attack on his special forces squad before joining the Red Shield. His father was also a member of Red Shield and was one of Saya's victims in the Vietnam incident. It is implied that he, along with Joel, are the only members that are descended from a line of Red Shield operatives. David's red crystal item is a cross.

After the Red Shield HQ Destruction
When the Red Shield's headquarters are destroyed and Saya is believed to have gone down with it, David sinks into a deep depression and becomes an alcoholic. Hagi helps David snap his world back into focus, though, after Hagi makes an observation about David's unhappiness, and he picks up his gun and is able to fight once more. During the investigations into one of Cinq Flèches's lab, he finds Julia and she tells him something about the research they are doing. He talks to her briefly again at Amshel's party, and lets her know that she will always be welcome back with the group.

In New York
Towards the end of the series, Dr. Collins tries to murder Julia, but David jumps in front of her, getting critically wounded himself. Julia keeps vigil over him in the hospital.

After the Feud Ends
Diva's death brings an end to the mission of Red Shield. After David recovers, he and Julia begin a romantic relationship. At the end of the series, Julia is pregnant with his child.

Personality
He is aware of Saya's past life and wishes to use her in the struggle against the chiropteran.

David tends to be straight-faced and serious, with a somewhat cold personality. However, he also assumes an unofficial guardianship of Kai and Riku, and would be instrumental in helping Kai come to terms with what Saya is and with Riku's conversion to a chevalier. He seems to take a particular interest in helping Kai grow up to be a strong man who can support Saya and Riku as their brother, despite their unusual natures.

Weapon
Smith & Wesson Magnum: David wields a Smith & Wesson Model 500 magnum revolver as his primary weapon. Carrying a handgun this powerful and large is unusual for an agent, but since chiropterans cannot be killed by normal means Red Shield personnel must rely on the knockdown power of their guns to keep the monsters at bay.

SPAS 12: David occasionally uses this shotgun to fight random chiropterans. He is shown to use it during the Yanbaru operation.

Trivia

 * In the Omake Manga, David appears to be a fan of cats.
 * Unlike in the anime, David is shown to be cold and harsh towards Saya in the manga. He sees her nothing but a weapon.