Does stabbing yourself end Suggestion if it was cast by another PC?

Question

Another PC, a Bard, casts Suggestion on my Barbarian. I failed the Wisdom Saving Throw and was given a specific task to fulfil, for example "go back to the boat".

When the Barbarian fulfils the specified task will it:

A) end the Suggestion spell right there, and allow me to move freely again?

or

B) will the Bard get to maintain Concentration on the spell for 8 more hours and only then end the spell?

And on the off chance that it continues, if I were to stab myself will the spell end? Can I stab myself for it to end, because companions stabbing me would end it right away?

Answer 1

You can't actively resist a spell you are not aware of

If you failed the Wisdom saving throw, that means you don't know you are under the spell effect.

Can I stab myself for it to end

What "it" do you want to end? The bard has merely suggested you to go to the boat, and you are pretty sure it is what you really should do. There is no single reason for doing stupid things like, you know, stabbing yourself.

Answer 2

Word your orders carefully...

If the suggested activity can be completed in a shorter time, the spell ends when the subject finishes what it was asked to do. - Suggestion, PHB, p279

The key element here is defining your task appropriately. If you tell somebody to do something that has a finite end, they stop doing it as soon as the task is complete.

In your example, the spell ends automatically as soon as the Barbarian reaches the boat. If you want to keep him there, rather than just slow him down with a bit of travel, the appropriate command is "Stay on the boat." As long as the caster maintains concentration, the target will stay there until the spell ends. Even better would be "Guard the boat," because once the spell wore off, the target is less likely to wonder "Why the heck have I been here for eight hours?"

Anecdotally, I've used suggestion to correct the course of a corrupt investigation. In one of the DDAL modules, the characters are framed for a murder. I got close enough to the lead investigator to use suggestion to tell him "We're innocent until proven guilty; do your job the right way." By studiously avoiding situations where she might lose concentration, my bard was able to keep the city guard at bay while the party conducted their own investigation.

Hit me baby, one more time...

If you or any of your companions damage the target, the spell ends. - ibid

The intention of this passage is to block suggestions like "stand still and do nothing" to prevent targets from defending themselves. The entire point of the spell is to make the target do things that seem reasonable.

Pay no attention to the man behind the curtain...

Unless a spell has a perceptible effect, a creature might not know it was targeted by a spell at all. An effect like crackling lightning is obvious, but a more subtle effect, such as an attempt to read a creature’s thoughts, typically goes unnoticed, unless a spell says otherwise. - Targets, PHB, p204

The suggestion must be worded in such a manner as to make the course of action sound reasonable. - Suggestion, PHB, p279

There's no reason for the barbarian to want to stab himself, because he has no way to realize he's under the effects of a subtle magic like suggestion. If he failed to save, he believes he's taking a reasonable course of action.

Attempting to stab himself to get out of the spell is metagaming, pure and simple - using out-of-character information ("the character is under suggestion") to drive in-character action ("the character stabs himself").

Answer 3

Suggestion includes this clause:

If the suggested activity can be completed in a shorter time, the spell ends when the subject finishes what it was asked to do.

So yes, if the Barbarian completes his task, the spell will end immediately. As for your second question:

If you or any of your companions damage the target, the spell ends.

So the real question here is whether the Barbarian still counts as a "companion" of the Bard when the Bard is using magic to enslave him. That, unfortunately, you're going to have to ask your DM. There are no rules for what causes someone to count as a companion, so your DM will have to make a ruling based on the situation.

Answer 4

Suggestion:

You suggest a course of activity (limited to a sentence or two) and magically influence a creature you can see within range that can hear and understand you... If the suggested activity can be completed in a shorter time, the spell ends when the subject finishes what it was asked to do.

As for stabbing yourself:

If you or any of your companions damage the target, the spell ends.

Either doing damage to yourself or completing the suggested task will finish the spell early, assuming the bard is your companion. So the effectiveness of stabbing yourself boils down to if you deem that the Bard is your companion at that point in time, which is not concrete.