After you've spent an hour designing the look of your Baldur's Gate 3 character, surprise! You have to do it again, this time for a "guardian." You're not told anything about who this guardian is or what role they play, just that you need to select a look for them.
I figured the guardian would be some mysterious presence in my story who I'd meet just as soon as I'd forgotten about creating them, and that's approximately right. At least one player I know got the wrong idea, though, and wandered around trying to find their guardian, assuming they were a bodyguard companion to seek out. Nope!
After you design your guardian, you can forget all about them. You won't find them hanging around on the nautiloid or beyond, so there's no point in looking, and you can't miss your guardian when they do show up. That's all you need to know to start the game, but read on if you want to know more about how this "guardian" fits into the story.
I've met my guardian, but I have no idea what their ultimate significance is, because I'm still in Act 1, which was already available in the early access version of Baldur's Gate 3. I can't spoil anything big from later in the game, then, but if you don't want to hear any more about the plot of Act 1, now's the time to alt-tab back over to the character creation screen, make your guardian look cool (or not), and start the game. Act 1 spoilers follow...
So, who is this guardian? (Act 1 spoilers)
The guardian first appeared to me in a dream during a long rest fairly early in Baldur's Gate 3's first act, while still camping in the druid grove. Standing in a field of asteroids and stars and surrounded by an abstract battle, she instructed me not to have the mind flayer tadpole removed from my head. Nothing can be simple, can it?
The supposed "guardian" said that she's been protecting me, revealing in a flashback that she's the reason I survived the nautiloid crash. She then insisted that I learn to harness the parasite's power in order to save the world, and that if I do, she can prevent it from turning me into a mind flayer.
Up until this point, removing the tadpole is the obvious number one priority with no alternative, so this really complicates things. Is it going to turn me into a mind flayer or not? And who is this Guardian the guardian of, me or the tadpole? The only good news is that you're not alone in this quagmire. When I woke up, I found that all my companions had experienced similar dreams that night.
Also in Act 1, we learn that a nearby cult is worshiping someone called The Absolute, and that the cult's goblin leaders have mind flayer parasites in them, too. But the guardian isn't asking you to gather an army like The Absolute apparently is, so who's talking to the goblins? Is it the same entity, tricking us? Or maybe it's the tadpole itself, trying to convince us to give in...
The second time my guardian, aka the "dream visitor," appeared to me, she explained that The Absolute is using the tadpoles to control the cult's leaders, and that they can be turned into mind flayers at the snap of a finger. She claimed that she, too, was infected, which is part of the reason she can protect me from the transformation. The other is that she stole some powerful magic from someone who wants it back, which is why she's always in the middle of a fight when she gets on the dream phone.
She's stuck wherever she is, or at least that's what she claims, which is why she needs me to do her work in Faerûn. The instruction is the same: use the tadpole, become more powerful.
I still have no idea whether or not to trust her. A possibly relevant side note: In an early version of Baldur's Gate 3's early access release, the guardian was pretty different. They weren't referred to as a "guardian" in character creation, were more seductive, and didn't come to you from the CGI set of a Thor movie. They wanted the same outcome, though: for you to embrace the tadpole.
One thing I can't accuse Baldur's Gate 3 of is being predictable: I really don't know how this is going to play out. Now that the full game is here, we can finally learn the truth together, and I intend to get on with the main quest just as soon as I finish talking to absolutely everyone in the starting area, animals and dead people included. It might be a while.
For more theorizing, fans have recently been speculating on the guardian's identity in this Reddit thread.