Here's some background to the situation, which I believe may relate to the problem. It should help some people answer the question.
I play a small game of DnD with some friends named Lorry, Kevin, and Charlie (all pseudonyms, Charlie is the DM). We have only been playing together for a few sessions, so all of our characters are only just beginning to poke around in the fifth level.
The problem can trace its roots back to two sessions ago. We were all battling some orcs in a ravine, when Lorry got knocked unconscious and, as a result, killed.
This wasn't exactly a surprise. Lorry's character was a wizard, and constitution was hardly his strongest stat. So, doing the best me and Kevin could on our own, we tried our best to clean up the rest of the orcs even with our comrade dead. Once we were done with that, we spent practically the rest of our session creating Lorry a new character, then making up a quick roleplaying gimmick to add him to our party before the next quest.
The thing is, when our next session date rolled around, Lorry got tied up with other things and couldn't make it. However, because I had invited a new person to our table (whose false name shall be Jim), Lorry told us to just play despite his own absence, and that he would just catch up next session.
We did, and consequently got a lot done. Me, Jim, and Kevin finished a quest, and even managed to level up.
Now here's an important part: While Charlie is hardly a rule stickler (especially with roleplaying), he likes his campaigns to make as much sense as possible. As a result, he made an executive decision in that session and placed Lorry's new character in NPC mode.
Under normal circumstances, Lorry's character would be a level-1 wimp, so him being under NPC mode wouldn't make any difference to the party. However, these were not normal circumstances. We were using an alternate, homebrew version of gaining XP that would have doomed Lorry's character to a life of endless frustration and constantly trying to get on the rest of the party's level (no pun intended).
Charlie, being a good DM, did not want that to happen, so he allowed Lorry's new character to automatically start out with the same amount of XP that the old character previously had. (That's part of the reason that creating Lorry's new character took so long in the previous session.) Charlie did the same thing for Jim when he decided to join.
Why is all of this significant? Well, it meant that Lorry's character wasn't a pet that we had to protect, but rather a pivotal fighting force on our team. He absorbed and dealt a lot of damage over the course of our session, even healing Jim's character at one point when he almost got killed.
All of us, even Charlie, really liked Lorry's new character. So we didn't understand why Lorry wanted to change it.
I see Kevin and Lorry outside of our DnD sessions on a regular basis, and they are pretty good friends, so I was recently surprised to find them arguing with each other. (Well, 'arguing' is probably the wrong word; there was no anger behind their words. It was more like they were in a fierce debate.) When I approached them, I learned that they were talking about Lorry's new character.
Lorry told me that he had never intended his current PC to be a permanent one. He claimed that it had been meant to be a "placeholder character," one that he would only have played in until he had formed his "actual character," which he actually intended to use. Making his 'real' PC would have apparently taken longer to create than simply making his 'placeholder' one, so Lorry said he instead had opted to create the placeholder until he could find time to create his real PC later.
The thing is, in the ample amount of time that had passed since our last session with Lorry, he'd had enough time to create his real PC. As a result, he said that he personally had no reason to keep his other one around, but because the group liked it and it made more sense for the story, he would just have his placeholder PC stay in the group, but on NPC mode.
Kevin did not like this at all. He said that Lorry can't expect to be able to just make free party members (especially NPC ones), as he claimed it would disbalance our campaign. Kevin told Lorry that he would just have to wait until his original placeholder PC died, then afterwards he could use his real one in its place.
It is important now to bring up a certain fact about Lorry. He is (for lack of a better term) not a person of integrity, or at least not in games. I've known him to use console commands in certain multiplayer games (which shall remain nameless) to 'break the game' in his favor. He will even defend and justify those actions later, calling them "exploits" rather than cheats, and sometimes even go behind both Kevin and my backs to use them.
Lorry is not a bad guy, it's just that he is a real letter-of-the-law person rather than a spirit-of-the-law person, and in this situation, it is really beginning to show. No sooner had Kevin proposed the 'wait-until-you-die' rule than Lorry said that he would have his character commit suicide as soon as he regained control of it. When Kevin banned that and other intentional deaths, Lorry said that his character would just "coincidentally fall off a cliff", as if he had no control over whether that happened. Then, when Kevin also banned that, Lorry finally said he would just go in as his new, 'real' PC and then attack and kill his old one.
Kevin knew he wouldn't be able to talk Lorry out of that plan, so he turned defensive and told Lorry that if his PC tried to randomly kill our companion member, we would definitely have to kill him (considering that kind of thing doesn't go over well in adventuring groups). Lorry then said that he would gather help (from Jim, presumably), so Kevin said that he would enlist me and back the old character... and the conversation didn't go anywhere productive from there.
We are planning for our DnD group to almost double by next session, with pretty much each of us bringing a new member. I have heard both of them separately say that they are planning on recruiting the new members to their cause, but I really don't want to start a civil war.
Which brings us back to my question (I bet you forgot what the question was.) How do I prevent Lorry from abandoning his PC in favor of a different one?