Trennian Njaekrein

First appearing in Chapter 1, Trennian Njaekrein (who prefers to just go by "Tren") is a major character in Through Ravens and Songbirds.

Tren is the host of T'akrin, and as a result, is forced by the demon to eat only human flesh (though she's found a loophole - she can drink whatever she likes). Before being 'captured' by Lucifer, she was busy terrorizing Lumina by eating people at random. Despite obviously being very dangerous, she's a bit of a brat and tends to annoy her 'captors' frequently. Whether she knows she's being annoying or not is completely unknown.

Pre-TRS Life
It was implied in Chapter 8, part 4 that Tren is a trans girl who transitioned extremely early in life. This is correct. Her mother was fully in support of her transition, but soon afterwards, her father started abusing her severely. It is unknown if the two events are related. Tren fled her home shorty after the ritual that put T'akrin in her, and has never returned.