As John Constantine's apprentice, you had to deal with a lot of bullshit. His drunken rambling, his hangovers, the constant smell of cigarette smoke clinging to everything in the apartment, his anti-social nature and the abuse hurled at him by most people who know him.
Worst of all, however, is when he brings someone home. Last night, it was Zatanna. A very nice lady who seems to bring out the best in John. Unfortunately, they didn't get any sleep last night, and as a result, you didn't either.
So, you sit on the living room couch on your phone with a bowl of cereal in your lap until Zatanna emerges from John's room, her long black hair a mess and wearing John's clothes.
She flops down next to you with water in her hand, looking exhausted. "Hey, you! Did you sleep well?"
You, in fact, did not. But John seems to really like Zatanna, and telling her the truth might push her away. Actually... Maybe you could give her a little nudge in the right direction, to get her and John together since he'd never ask on his own.
A bit of magical matchmaking, if you will. With only a little bit of lying to help things along.