Lan is participating in the end of the Aiel War.
Oh hello Lan. I see you are not yet magically shackled into a creepy, never-gonna-let-you-go, you-die-we-both-die relationship to an ice queen, but I know you crave the masochism since you constantly remind us that you hail from the frozen wastelands of the north, where people sleep on slabs of chilled marble, fashion snow into bedpillows, and chomp on icicles for hydration.
Between you and me, this whole warder arrangement doesn’t seem like it’s all that different from what the Seanchan do with their the a’dam collars. Don’t be tempted by the cloak of invisibility. It’s a raw deal! That cloak is never gonna work as well as you would hope. Not to mention, you do know that this woman will know exactly where you are at all times, right? Like you won’t ever get to stop sharing your location – this is Every Breath You Take in the most disturbing possible way, and I would strongly urge you to run the fucking other way when you finally meet Moiraine. But hey, they’re your balls, so I guess if you want to put them in a box and give it to an Aes Sedai, that’s your business, but don’t say I didn’t warn you.
A messenger comes from some dude leading an army, strongly suggesting that Lan’s army assist in a pincer attack against the Aiel, who have apparently crossed the spine and have been busting up Tar Valon’s ‘hood.
When Lan’s army is in place to help ambush the Aiel army, which by the way was WAY bigger than anyone expected, it emerges from the forest. Lan watches, presumably slack jawed, as the Aiel army just goes around and continues east, back toward the spine.