What would make me get less exp than my groupmates? We were both neutral, I'm "secure", have better charisma, and am lower level. The mobs were evil or neutral. It seems like I should be getting more not less. I've actually noticed this same thing with a couple different characters.

There's some weird code where if your level is a LOT lower than your groupmate(s) then you will get less experience. This is particularly the case if you grouped around someone so that you could group with a higher level person you would not normally be able to group with.

It's tied to the group leader.

It does not kick in against creatures to small to give the leader much exp. Which is why I will run lower groupmates through weaker monsters to close the gap in exp for a faster net gain as a group.

This seems to confuse a lot of people and I've got a bad habit of losing my temper and throwing out group mates who don't get it and bitch.

How many of that NPC you've killed (either lately or total, not sure, maybe a bit of both) can factor into your exp reward as well, i believe.