Lily P
Him would be Severus Snape. He'll point you at the books, have you read them, and then apologize for ... everything.
As far as explanations go ... I wish I had more of one. We've been pulled here at the whim of a playful god, and ... there's no going back, apparently. We're characters. Made up in someone's mind. I can't completely believe it, but ... it is what it is, I suppose.
And ... I don't know how there are multiples of us. It's happened with a few other people. Different time frames or something.
Sirius is here, by the by. He's not overly fond of me, but maybe he grew on ... you as time rolled on?