I read this series on 2014/2015 on oyster but I believe it is mug older. I remember it having a 70s/80s style cover
So it’s a series of four books where a group of Marines (definitely soldiers) are looking into the planet (I believe it is mars) and they are taking a scientist along with them, there is also a colony on the planet and there is a helpful alien that looks different than all the other aliens on the planet and also seems more intelligent.
They find an organism that heals anyone infected with it the main character is infected and is worried about what will happen if it gets back to earth she moves in with the alien at some point and they become lovers, the alien has two penises
So it’s a series of four books where a group of Marines (definitely soldiers) are looking into the planet (I believe it is mars) and they are taking a scientist along with them, there is also a colony on the planet and there is a helpful alien that looks different than all the other aliens on the planet and also seems more intelligent.
They find an organism that heals anyone infected with it the main character is infected and is worried about what will happen if it gets back to earth she moves in with the alien at some point and they become lovers, the alien has two penises