How much control does a Vampire Lord have over one of his Vampire Spawn?

Question

The Monster Manual section on vampires (p. 295) says:

Born from Death. Most of a vampire's victims become vampire spawn - ravenous creatures with a vampire's hunger for blood, but under the control of the vampire that created them. If a true vampire allows a spawn to draw blood from its own body, the spawn transforms into a true vampire no longer under its master's control. Few vampires are willing to relinquish their control in this manner. Vampire spawn become free-willed when their creator dies.

One of our PCs was bitten (and killed) by a Vampire Lord. If she were raised as a Vampire Spawn, what level of control (if any) would she retain over her character?

Are Vampire Spawn mindless zombies, that only do explicitly as told? Or do they retain some level of free will? What would be a good way (mechanically) to handle an unwilling Vampire Spawn?

Answer 1

The question seems to be essentially:

What does "under control" mean?

Does it mean the character is braindead while not receiving orders? Can he disobey any orders? While not receiving orders, what can he do if he's not braindead?

First Angle: Spells

Let's check what spells give you control over other creatures and how they behave.

Animate Dead gives you a zombie

If you issue no commands, the creature only defends itself against hostile creatures. Once given an order, the creature continues to follow it until its task is complete.

The same goes for Animate Objects, Conjure Elementals, etc...

So, for the situations where you "create" a creature from what was an inanimate object before (or a corpse), they are braindead. Note that the procedure to create a Vampire Spawn is similar to that of a Zombie or a Skeleton. So far, if you take this angle, your Vampire Spawn is braindead.

Second Angle: Attributes

But hey. Zombies, skeletons and elementals have the Int attribute of an animal, so yeah, they are braindead by default. Our Vampire Spawn has an 11!

So, how do characters with intelligence behave when being controlled? Let's check Dominate Person

If the creature completes the order and doesn't receive further direction from you, it defends and preserves itself to the best of its ability.

Well, that didn't help.

Third Angle: The Role-Play and the Game

Well, all these spells were intended for you to create a temporary combat minion. They don't actually have personalities, backgrounds or whatever. Probably that's why they are so blunt, not doing anything besides trying to survive. You can have Vampire Spawns that are just like that, combat minions to your Vampire Lord and that's all. But you seem to be interested in something else.

General rules I think everyone could agree on what being "under control" means:

• If given an order, the character will try to accomplish it to the best of its capabilities, preferably as intended by the ruler (meaning no wording play, unless actually misunderstood).
• The character can not try to do any kind of harmful action against its master.

I think these two basic rules are enough for you to role-play an "under control" character.

Specifically for the Vampire Spawn case, it explicitly says it has no free will (as he only gets free will when the creator dies), so an additional point would be

• They lack any kind of motivation to do anything besides surviving.

This last point is, IMHO, the one you can tamper about if you want to make a player have a Vampire Spawn character. They might have memories of their past lives and still have some feelings, motivations and maybe even morals, so, unless it breaks the first two rules, they might be able to do something other than sucking blood to survive and sleeping.

TL;DR:

The rules intend any kind of minion (Zombie, Vampire Spawn, Animated Objects, Conjured Elementals, Dominated Person or Monster) to have no free will and do absolutely nothing besides defending themselves and surviving. In the Third Angle, I try to suggest a more broad definition of "under control" than this completely-braindead-character. My suggestion seems to be consistent with the vampires in Curse of Strahd, which were mentioned by the OP in some comments.

Answer 2

To answer the various parts to your question:

Are Vampire Spawn mindless zombies, that only do explicitly as told?

I think your description answers that question to some extent.

ravenous creatures

So, there seems to be some level of free will, but driven by the desire for blood. They are going to act out when they need blood and likely wouldn't be completely controlled and frozen in case the vampire that turned them forgot to tell them to eat.

Or do they retain some level of free will?

It seems like a survival instinct would kick in and that when they need blood they are going to act out on their own, again see them being ravenous. I'd also go with the rules that are in place for Command and other mind control spells like that.

or if your command is directly harmful to it. (PHB)

So, in this case, the control that the creating vampire could exert wouldn't allow them to tell the NPC to jump off a cliff or do something directly harmful. And with that control, it wouldn't likely control every action

What would be a good way (mechanically) to handle an unwilling Vampire Spawn?

I would have them go with a wisdom saving throw. To keep the fun in the game, if you want to have a player who is turning into a vampire, they should always be able to resist. However, on a failed saving throw, they take X amount of psychic damage, and on a save, half as much. Then, I'd also personally go with the idea that the creating vampire knows where they are at all times and can command them psychicly. If the PC resists too often, the creating vampire might come and hunt them down. Or if they resit too much, they might end up killing themselves with psychic damage.

Answer 3

As you quoted, the vampire spawn is "under the control" of the vampire lord (without caveat or exception) and only upon the death of the vampire lord is it free-willed. It perfectly obeys every command that is given it. Its personality only affects how it completes those commands. It cannot disobey, as it explicitly has no free-will.

A PC that becomes a vampire spawn is now an NPC controlled by the DM, and the player needs to make a new character.

Answer 4

What I believe is meant by "under control" is that if the creating vampire gives a command, the vampire spawn has to follow it, no exceptions. They can probably exert that control telepathically as well, and it makes sense that the creating vampire would always know where the spawn is. That said, if there is no command given, the spawn can probably do what it wants unless specifically commanded otherwise. They also probably can't knowingly betray/attempt to harm their master either.

I had a character that was under another's control. Not a vampire spawn, but a dhampir that was under the control of his father (a vampire lord), and that's how the control worked.