What if one player kept whispering in the other's ear?

Agreed, give a chance to flip at the beginning of every turn, since that’s when reactions and most abilities/spells reset. Also, to further reduce the chance of one player holding the character too long and to add a little fun tension: instead of a coin flip, in order to take over, the player not presenting makes an unmodified DC10 check that decreases by 1 with every failure and resets on a success.

Also makes sense that in higher stress situations like combat, they'd be fighting for control more frequently than when they're chilling in camp.

So would the character have to carry two sets of gear and change with each personality switch? Would the warlock even have the strength to haul around a paladin's armor and sword?

Is there a name for this trope of cramming really wacky, difficult, high spotlight, stuff into a game like DND that doesn't especially support it? I usually feel bad because I want to encourage creativity, but I also don't want this guy to have 80% of the table attention while Bob the Fighter and Joy the Rogue are playing by the numbers.

Limiting skills and abilities to only one class of a multiclass character at a time is going make them fall behind very quickly. As a DM that is my only concern, love everything else!

Reminds me of the twins from Kingmaker.

I encourage you to try [Everyone is John](https://rtwolf.github.io/Everyone-is-John/) then.

Might be fun to add a check to it. Maybe something akin to a concentration check that they have to roll when they take damage to hold on to their connection to their patron. Failure means they flip.

That sounds like a blast

Wouldn't that character get super nerfed fast? Even at an even split of class levels you'll be half the class level of the rest of the party, with only hp/proficiency keeping up.

Main Character Syndrome

Sometimes it's just about having fun.

French rpg bloodlust is famous for God Weapon having their own urges but not being able to indulge them without a human bearing the weapon. Leading to the poor human getting some power based on what the weaponk let them do, while having a weapon begging them to indulge in violence, lust or any other awful sin. Having a player having the weapon and another one the bearer open the road to pretty interesting roleplay

That and the changing every in game hour. I'm rarely tracking time down to the hour, it would either slow things down if they try to make any kind of scene out of it, or we're just going to gloss over multiple changes, potentially making the whole thing moot. Then you get into a dungeon and someone might be locked out of "their" character for a large chunk of playtime.

This sounds like a fun character.

It sounds like the character has the same total level as the rest of the party, but can only use features from half of those levels, so it's going to be underpowered to the point of unplayability.

In 5e, if they took their first level as Paladin, they would gain Heavy Armor Proficiency. Having proficiency in heavy armor would allow a normal Lockadin to cast their Warlock spells in armor just fine. They also both heavily favor Charisma, and if the Warlock took Pact of the Blade or Hexblade, they wouldn't even need strength for melee. That's a normal Paladin/Warlock though, with this weird hotseat play they want to do, their self-imposed rules might not let them even use the other class' passive features, which could get awkward.

I actually did this once, only the good personality was a pacifist healer who was a liability in combat due to her aforementioned pacifism and her oath to help anyone who asks for it occasionally helping our enemies, and the evil personality was a sociopathic battle hungry sorcerer who just wants to cause as much mayhem as possible. Mechanically speaking, the evil one surfaces in high stress situations (I have to fail a con save for it to take effect) and I automatically revert to the good one upon falling asleep or otherwise losing consciousness in some way. I ran all of this by my dm to make sure it wouldn't screw over the party too much or be too powerful. It was my favorite character thus far.

Did your party feel the need to knock out your character from time to time?