Are you capable of writing lyrics?
Me, personally, unfortunatelly not. I can write a melody for the lyrics and I can even edit lyrics so it fits the song and melody. I can even write a good lyrics theme in cooperation with the artist. I can both start writing the music and then adapt the lyrics or I can start with writing melody for the lyrics and then write the music around it. But I have several talented lyricists around me so the collaboration is definitelly possible.