Well you guys were all pretty helpful. I had the session last night and it ended up pretty epic. Before I tell you what happened I need to offer a few more details that I didn't in the original post.
The barbarian's weapon was a greatclub that was literally a bone. (very low-tech world) From first level on the barbarian had planned to take warlock levels and he wanted the bone to be the source of his powers. We talked out of game and it was strongly implied that the bone was "evil" and sentient. So he took his warlock levels and started carving runes in the bone that would represent his spells. I didn't give the bone any special powers other than he could use it as an arcane focus. It also had not reached "full sentience" yet. I still have yet to figure out what that would be. But the bone would turn cold when the barbarian did something it approved of. It would turn cold and be painful to touch in a way that the barbarian enjoyed.
This evil bone was the real reason the druid did not like the barbarian. The bone AND the barabrian were both a bad omen in his eyes. The druid made his sentiments very public and the rest of the village generally agreed with him.
Cue the party cleric....
The party cleric (Nature domain) was a subordinate to the druid. The druid followed a sect of their common religion that the cleric was beginning to find suspect. The cleric started to view the druid as a false prophet and was thinking of ways to dispose him. The cleric and the barbarian had a casual meeting one day about what they can do about the druid. The meeting left with the barbarian saying "I'll take care of it" and the cleric wondering what that meant. "Surely he wasn't thinking of...."
The next day the druid was found brutally murdered.
So I planned the next session based on a lot of the advice you guys gave me. I had the party ranger do a little investigative work. Had some roleplay with the party bard. (who is actually the barbarian's twin sister) She had reasons to start suspecting him. Interrogations were had here and there. I was running the whole session as one long 4th edition style skill challenge with the objective being: barbarian gets away with it. I set the difficulty pretty high, but he was getting some successes under his belt. Until the cleric just straight up threw him under the bus to one of the council members. OF COURSE she did. Even though she suspected the druid was starting to lose it, he was still her superior and mentor AND SHE ABSOLUTELY KNEW WHO DID IT, because of her meeting with the barbarian. Now I was taking the players in and out of the room so they couldn't hear what others were talking about. The barbarian did not know though cleric did this. He was suspicious though. He confronted the cleric in the temple.
I had the cleric's younger brother in there consoling her. When the barbarian approached the cleric they roleplayed an excellent argument and the cleric flat-out said. "I turned you in. YOU killed the druid and I told the council." The barbarian rages, one shots the cleric's brother, and PVP ensued. I was very uncormfortable. It was awkward. This is the first campaign I have ever ran that resulted in PVP.
The cleric very intelligently casted Sanctuary and was able to run out of the temple and call for the guards. The guards came and they and the cleric made relatively short work of the barbarian, though the barbarian did kill one of the guards. The cleric had landed a bunch of her spells (Guiding Bolt) and he went down. One of the guards finished him off with a spear to the gut. No more Barbarian.
Now a couple interesting things happen. The first was when they were deciding what to do with the bone. The cleric picked up the bone and when she did I told her: "you grab the bone on one of the carved sigils. It's red hot, and your hand starts to smoke and blister. You drop the bone and the sigil is burned into the palm of your hand."
The second interesting thing that happened goes ALLLLLLL the way back to the very first session. The party had found a large egg (It was an axebeak) and the barbarian kept it in a custom made woven backpack and wanted to hatch it. I immediately wrote in my notes "roll d20 once everyday, and on a 20 the egg hatches." (you see where this is going) After the barbarian was killed and they were discussing things, I thought to myself, "Hey. I forgot to roll for the egg today." I pick up my 20 sided die, gave it a roll and BAM. OF COURSE it's a 20. It was amazing. I just laughed out loud, and began to describe the hatching of the egg. He kept it with him in a custom made basket/backpack.
The party bard took the baby axebeak as a token of her dead twin brother. She blamed the bone on his descent to evil and has vowed to discover it's origin and enact vengeance somehow. Meanwhile the bone was packed up in a very "Raiders of the Ark" style and is currently being stored in the temple.
So three pretty great hooks came out of this:
1. The pet axebeak (I guess that's not really a hook)
2. The cleric's scar from the bone.
3. And the who/what/where/why/and how of this bone <----I still have no idea
I do think that I am going to ask the barbarian player what his dying curse on the cleric would be. I'll let him come up with a power for the cleric but with some kind of negative aspect to it. My first thought was to give the cleric a power that does an INSANE amount of damage (20d6) but that damage is done to her as well. No save. Maybe it starts at d6 but goes up a d6 everytime she uses it.
What do you guys think?