Baldur's Gate 3 has the soul of a doomsday prepper in the sense that the RPG is always ready for even the most unlikely scenarios, as one player recently demonstrated with a rare Astarion scene most people miss during a typical campaign.
Here's the situation: it's possible that, after you long-rest multiple times in Act 3, vampire spawn will ambush your camp with the hope of returning Astarion to his sadistic master Cazador.
And it is also possible that – as Reddit user Soft_Stage_446 explained in a thread – you can become Astarion soon after this, but only if you meet a very specific set of conditions.
First, there's the matter of triggering the vampire spawn ambush, with all of the long-rests. Then, you have to intentionally allow the spawn to defeat Astarion in combat, which is surprisingly difficult, considering how ridiculously simple it is to beat up Astarion's siblings.
If the spawn manage to take down Astarion, they'll bring him to Cazador's grimy palace kennels From there, even if you aren't playing with Astarion as your pre-baked Origin character, which others who have found this rare scene assumed was a prerequisite to unlocking it, you will experience Astarion's abduction from his perspective.