Inspired by this question: Can a Druid pull a target through other creatures with Thorn Whip?
That Q&A concludes that it is possible for two creatures to unwillingly share the same space; for example, one creature could be pulled by thorn whip into the space of another creature.
Once the thorn whip caster's turn is over, when it is one of the other two creature's turns (either the one who was pulled or the one's whose space was invaded), they will of course start their turn in another creature's space.
From the PHB, p. 191:
Whether a creature is a friend or an enemy, you can’t willingly end your move in its space.
Are they allowed to end their turn in the other creature's space if they don't use any movement, or must they move out of the space (if they can; i.e. they have movement)?
- What happens when your movement is set to zero while attempting to move through a friendly space? (accepted answer seems to imply that the other character would have to move, but this is not supported and comments dispute that unsupported point; also, that question is about the character moving on their turn, mine is not)
- Does the rule that you cannot willingly end your move in another creature's space force or prevent certain actions? (not the same as my question as it talks about sharing space on the creature in question's turn, whereas mine is about not moving on your turn to avoid this)