The Haine Twins are greyscaled versions of Len and Rin.
Lin is the dark version of Rin, and is quite aggressive but will gradually become nicer if you become friends. She is also very tomboyish and doesn't like wearing dresses and has a habit of yelling at people for no reason, but after a few days (or even weeks) she'll think about it and apologize.
Ren is tall, and dark. He looks exactly like Len, but has darker hair and clothes. He is usually very calm and cold and usually won't talk to you when you try to talk to him, and will instead ignore you, but he is actually very welcoming and nice once you become his friend.
Their voice are Len's pitched down for Ren and Rin's pitched higher for Lin. Their voices are pitched an octave lower than the original Rin/Len voice.
So far, there is no original song nor special voice configuration for them. The fans usually only pitched the song to get their voice.
- -10 on audisity works best especially with a hard voicebank