He wants a relationship with you on some level, whether it is as lovers, friends or as enemies.

The never ending texts and calls are an attempt by him to provoke you into responding, which would signal the resumption of a dialogue (in his mind, anyway) and therefore the payoff he is seeking.

In a way, you are still in a relationship with him. Your curiosity keeps you doing the block-unblock-block shuffle.

Are the texts/calls the only way he is in your life? I'm getting a real "stalker" vibe from him.