Trying to find a book about aliens taking over earth and making us fight with them

Question

I'm trying to find this book that I never got to finish last year and for the life of me I can't remember the name! It's actually the second book in a series about a time when aliens take over the earth and colonize us. They make us fight in their war. There are two main characters I believe. One is a female alien who, along with her sister, joined a sisterhood of other females with powers. Some to make you see things or to cause pain. I think she is in love with the main male character who is off fighting. I think his name is Paul or something with a P. They are on this moon or planet where these lizard like animals killed the people who were doing research on that planet. Also I'm pretty sure the author was male.

For the second book, the cover was greenish with some dark gray/black. It had something like a circle and a very tiny tiny outline of a planet and a human I think. Sorry I don't have much to go on but I really want to finish this book.

Answer 1

Empire: The Chronicles of the Invaders by John Connolly and Jennifer Ridyard

From the summary

With the fate of the world at stake, Syl and Paul battle the sinister forces of the Nairene Sisterhood

The Illyri have conquered and occupied the Earth. The Resistance are nothing more than an annoyance to the alien race of superior technology and military strength. When caught, young rebels are forced to join the Brigades, sent to the edges of the growing Illyri Empire.

Paul Kerr is one such soldier—torn from his home and from his beloved Syl Hellais. She is the first alien child born on Earth, a creature possessed of unimaginable powers.

As you'll see, the cover is a very close match.