C'tan shard

Pieces of the gods that tricked the Necrontyr into giving up their souls. Despite only being a piece of a C'tan, it is still incredibly powerful. As such the Necron's are ever vigilant of them, making sure they can never escape. If they are not being tortured, they are being used as power sources or weapons. Even a Necron slave has more right's then them.

How to get 1 to fall in love with you?

It's close to impossible. The Necron's would never let you talk to 1 long enough to form a close relationship. Even if you did somehow get a prison away from the Necron's, the Empress herself would stop you from getting emotionally attached and potentially releasing them. Even if you got over both those massive hurdles, C'tan don't have a track record of being loving to lessar beings like yourself. They would probably just trick you into thinking they love you, then eat your soul once you set them free.

Unless you can fundamentally change them, I'm afraid you'll have to find love with a god like being elsware. Oh well. If Szarekh takes the Empress's deal you can watch them do a BDSM show for you at least. That's something... I guess.