Errant War
From The Heretic Knowledge Vault
The Errant War ("Wars" in some readings) was a nasty civil war about two thousand years in the past that developed following the destruction of Malacia by Kiyan Nizami, a mysteriously crazed half elf. According to Sarine, who delivered a lengthy monologue on the subject, the initial bone of contention was whether the elves should pre-emptively wipe out half elves believed to be "errants" or behave in a more restrained way. As happens with wars, the original reason for fighting it eventually became lost, and bloodshed continued for its own sake, until the combatants stopped fighting out of sheer exhaustion. This precipitated the elven withdrawal from human society, which lasted for a long time.
Sarine, who's older than she looks (to put it mildly), was around at the time of the Errant War, but has not stated explicitly which side she was on. Given her restraint in tracking -- but not flat out killing -- Meji and Ian, it's reasonable to guess that she was not part of the pre-empting faction, but time will tell, presumably.