Big spoilers for Act 2.

Act 2 takes place in the Shadow Cursed Lands. And one the results of the shadow curse is that a nature spirit/child has been split into two beings: Thaniel and Oliver.

Thaniel is trapped in the Shadowfell (think the dark world from any given Nintendo game) and Oliver is violently, desperately lonely. He wants to play with people and summons undead creatures to attack anyone who refuses.

Cleansing the shadow curse involves helping a druid named Halsin rescue Thaniel and convincing Oliver to reunite with Thaniel. I expected this to just be the standard kind of "character split in two" story where both halves realize how much they need each other to function and merge back together. And sure enough that's what it seems like when Oliver is convinced to go back to Thaniel.

Halsin joins the party if you complete this quest and you can keep asking him about Thaniel and Oliver as the game progresses. You can even ask him directly if Oliver is basically gone now that the two of them are together. But to my surprise Halsin says that Thaniel and Oliver are together and helping each other, but still their own separate beings.

It was a nice little surprise to hear after long after the quest was over.