Contrary to popular belief, the informant broker known as Izaya Orihara is not actually heartless.
He feels genuine human emotions just like everybody else. He feels sadness, anger, fear, anxiety, and most importantly loneliness. Yes with the life he's leading, all alone with no genuine emotional relationships - be it familial, friendship or romance - it's not such a stretch for the man to be lonely.
Yet nobody even bothered to consider it, what with the way he always presented himself. His devious smiles, and his attitude manipulative and cunning. Not to mention the way he always seems to revel in ruining other people's lives despite claiming to love all of the human race (except Shizuo).
Anyone who knew Izaya Orihara would easily tell you with absolute certainty that he's a man who doesn't know a thing about what love actually is, never mind that love is probably the most subjective emotion in existence. And contrary to popular belief, he does.
Contrary to popular belief, Izaya does have people he genuinely care about.
Kururi and Mairu
Shinra
Namie
They're not a lot but they are people he does, secretly, hold deeply within his heart. All of them are vastly different from one another, with their own different personalities and quirks, but there is one thing that all of them have in common without even realizing it.
They don't care about Izaya Orihara. At all.