As Lucien Renren, DS appears as a 14 year old boy with short, soft black hair and big, dark eyes. After transcending into Lucifer, Lucien gains twelve brilliant angel wings and goes completely nude. He maintains his facial features and physical stature, but gains a vibrant aura around his body.
Base Dark Schneider usually wears combat armor over olden clothes. He is tall and lean, with long, flowing white hair and stark blue eyes. He has thick black eyebrows and noticeable vampire teeth. Dark Schneider is widely regarded as very handsome and attractive by all the women in the series, and he frequently mentions his own looks in that way as well. Darsh is also known for randomly going nude and has no problem appearing in public without clothes.
As Majin Dark Schneider, Darsh's body undergoes a drastic transformation. His appearance becomes that of a grotesque and satanic demon with numerous spiky protrusions along his limbs and appendages. He grows a long spiky tail and large wings, and the new layer of his skin is a dark rust color. An additional tattoo of "666" appears on his chest and his entire torso is replaced with a mouth, complete with multiple rows of viciously sharp teeth. Darsh also grows large claws and talons with something that resembles horns along the sides of his head. He shows markings and tattoos on his face as well.
When Darsh summons Dragon Knight Lucifer, his body becomes plugged into and fuses with wires and technological contraptions. The DKL armor itself is a massive, metallic, dark colored three-headed Dragon.
D.S. has another body transformation in Adam of Darkness form. He dispenses of the monstrous, jagged spikes that appeared all across his body in Majin form, as well as the tech he fused with as the DKL host in favor of regular flesh. He is again completely naked but retains his wings, though they are larger, darker, and more feathery.
Darsh is a narcissist in every manner of the word. He is also extremely selfish, egotistic, unpredictable and savage. He constantly boasts about not just his looks, but also his capabilities. He is also a womanizer and has had many female partners. Dark Schneider has little in the way of redeeming qualities since his moral compass is skewered, but he loves combat and fighting in general and also has unparalleled determination. However when he gets into a fight, he becomes extremely unpredictable. We see this hold true when Darsh fought Konron. After already defeating him and decapitating him, Konron pleading for his life but Darsh ate crunched his head with his abdomen mouth. His irrational behavior also extended to his battle with Uriel, when Darsh resurrected Uriel's sister Amreal after their fight.
When in combat, Darsh likes to completely and utterly destroy his opponents. He is prone to showing no mercy and has, on more than one occasion, literally tortured his opponents. However DS has a weak spot for women. He will usually not kill them, and if it's a woman he loves, he would even sacrifice himself to not hurt them. Such was the case in his battle with Arshes Nei when D.S. literally ripped his own heart out to stop the fight.
Darsh also loves sex, and his lust for women is so strong that he would do lewd actions even while fighting women. He ripped off Porno Diane's panties while fighting her and devised a special technique just to make her orgasm. His battle with Sean Ari also ended with him taking her virginity.
Despite all of his quirky qualities though, D.S. hold great value in his closest friends and would go to great lengths to protect them. But he is far from honorable and is in honesty regarded as a scoundrel by even Hagiwara.
Very little is known about Dark Schneider's background and origins outside of a rough outline of events. Hey may have been the Dragon Knight who defeated Anthrasax 400 years prior to the story, when the world was as technology advanced as it was in our modern age.