Logyn is the alter ego of Yozora.
For hypothetical and "lore" reasons... I'll just say... Logyn comes from a very dark place.. He doesn't do "friends", if anything he'd probably back stab them. He's a liar, a fiend and a trickster. He's a sick twisted evil conniving fuck.. filled with rage, anger and hate.. He doesn't care about the feelings of others. He'll cause anguish to others- sexual, mental or physical... He's a manifestation of the pain, turmoil, and neglect Yozora keeps dormant...
The only thing he exists for.. is to cause pain to others. He's evil, and the only way he'd get along with others if he was in company like himself...