I started Divinity EE recently with a friend and I have quite an annoying problem : my main character is more than 3000xp points behind so he stayed level 5 as the rest of the group is level 6. How can it be possible ? Is it just a bug ? We still have not completed the merc quests so it's not related to XP that we could've win only for certain characters.
This happens in my single player game when one character is not near the battle when an enemy dies. So your friend probably gained xp by killings things, or maybe by discovering things (that’s gives xp too) without your character being close to him.